diff --git a/src/AnalysisConfigFiles/IndexPropertiesConfig.yml b/src/AnalysisConfigFiles/IndexPropertiesConfig.yml
index 87ce5705d..4f268587a 100644
--- a/src/AnalysisConfigFiles/IndexPropertiesConfig.yml
+++ b/src/AnalysisConfigFiles/IndexPropertiesConfig.yml
@@ -156,6 +156,16 @@ AvgEventDuration:
   NormMax: 1000
   ProjectID: Acoustic Indices
   Units: "ms"
+SpectralCentroid:
+  Name: SpectralCentroid
+  Comment: "Av of all frame spectral-centroid values in audio segment."
+  DataType: double
+  DefaultValue: 0.0
+  DoDisplay: true
+  NormMin: 0.0
+  NormMax: 1.0
+  ProjectID: Acoustic Indices
+  Units: ""
 #EventsTotal:
 #  Name: Event Count
 #  Comment: "The total count of acoustic events per minute of recording."
diff --git a/src/AudioAnalysisTools/Indices/IndexCalculate.cs b/src/AudioAnalysisTools/Indices/IndexCalculate.cs
index c2b7e01d8..5e0fcdd88 100644
--- a/src/AudioAnalysisTools/Indices/IndexCalculate.cs
+++ b/src/AudioAnalysisTools/Indices/IndexCalculate.cs
@@ -383,6 +383,10 @@ public static IndexCalculateResult Analysis(
             double entropyOfPeaksSpectrum = AcousticEntropy.CalculateEntropyOfSpectralPeaks(amplitudeSpectrogram, lowerBinBound, middleBinBound);
             summaryIndices.EntropyOfPeaksSpectrum = 1 - entropyOfPeaksSpectrum;
 
+            // vii Calculate SPECTRAL CENTROID for the recording segment. This is obtained by averaging over all frame spectral centroids in segment.
+            var centroidArray = SpectralCentroid.CalculateSpectralCentroids(amplitudeSpectrogram, nyquist);
+            summaryIndices.SpectralCentroid = centroidArray.Average();
+
             // ######################################################################################################################################################
             // (C) ################################## EXTRACT SPECTRAL INDICES FROM THE DECIBEL SPECTROGRAM ##################################
 
diff --git a/src/AudioAnalysisTools/Indices/InitialiseIndexProperties.cs b/src/AudioAnalysisTools/Indices/InitialiseIndexProperties.cs
index b0dd2280a..ded1b8350 100644
--- a/src/AudioAnalysisTools/Indices/InitialiseIndexProperties.cs
+++ b/src/AudioAnalysisTools/Indices/InitialiseIndexProperties.cs
@@ -20,11 +20,11 @@ namespace AudioAnalysisTools.Indices
     /// TO CREATE AND IMPLEMENT A NEW ACOUSTIC INDEX (BOTH SUMMARY AND SPECTRAL INDICES), DO THE FOLLOWING:
     /// 1) Create a KEY or IDENTIFIER for the index in the list below. Always use this key when referencing the index.
     /// 2) Declare the properties of the new index in the YAML file: C:\Work\GitHub\audio-analysis\src\AnalysisConfigFiles\IndexPropertiesConfig.yml
-    /// 3) Modify the method SpectralIndexValues.CreateImageOfSpectralIndices(SpectralIndexValues spectralIndices) to incorporate the new index
+    /// 3) if necessary, modify the method SpectralIndexValues.CreateImageOfSpectralIndices(SpectralIndexValues spectralIndices) to incorporate the new index
     /// 4) Calculate the INDEX some where. In the case of Acoustic Indices, they are calculated in the class IndicesCalculate.cs.
-    /// 5) Store the value of the index in the class IndexValues
-    /// 5a) e.g. for spectral index:   indexValues.AddSpectrum(InitialiseIndexProperties.KEYspectralENT, spectrumOfENTvalues);
-    /// 5b) e.g. for summary index:    indexValues.StoreIndex(InitialiseIndexProperties.KEYindexName, indexValue);
+    /// 5) Store the value of the index in the class SummaryIndexValues or class SpectralIndexValues, as appropriate.
+    /// 5a) e.g. for spectral index: indexValues.AddSpectrum(InitialiseIndexProperties.KEYspectralENT, spectrumOfENTvalues);
+    /// 5b) e.g. for summary index:  indexValues.StoreIndex(InitialiseIndexProperties.KEYindexName, indexValue);
     /// 6) Add lines into IndexCalculateTest.TestOfSpectralIndices() to set up testing for the new index
     /// ==============
     */
@@ -54,6 +54,7 @@ public static class InitialiseIndexProperties
         public const string KeyActivity = "Activity";
         public const string KeyEventsPerSec = "EventsPerSec";
         public const string KeyAvEventDuration = "AvEventDuration";
+        public const string SpectralCentroid = "SpectralCentroid";
         public const string KeyHfCvr = "HF_CVR";
         public const string KeyMfCvr = "MF_CVR";
         public const string KeyLfCvr = "LF_CVR";
@@ -68,22 +69,6 @@ public static class InitialiseIndexProperties
         public const string KeySptPerSec = "SPTPerSec";
         public const string KeySptDur = "AvSPTDuration";
 
-        //KEYS FOR SPECTRAL INDICES
-        // Initially thought that these would be useful but as of February 2019 none used, so commented.
-
-        //public const string KeYspectralAci = "ACI";
-        //public const string KeySpectralBgn = "BGN";
-        //public const string KeYspectralCvr = "CVR";
-        //public const string KeYspectralEnt = "ENT";
-        //public const string KeYspectralEvn = "EVN";
-        //public const string KeySpectralOsc = "OSC";
-        //public const string KeySpectralPmn = "PMN";
-        //public const string KeySpectralRhz = "RHZ";
-        //public const string KeySpectralRng = "RNG";
-        //public const string KeySpectralRps = "RPS";
-        //public const string KeySpectralRvt = "RVT";
-        //public const string KeySpectralSpt = "SPT";
-
         public static double ClippingThreshold
         {
             get
diff --git a/src/AudioAnalysisTools/Indices/SummaryIndexValues.cs b/src/AudioAnalysisTools/Indices/SummaryIndexValues.cs
index 0e17f44d3..09d6699d4 100644
--- a/src/AudioAnalysisTools/Indices/SummaryIndexValues.cs
+++ b/src/AudioAnalysisTools/Indices/SummaryIndexValues.cs
@@ -135,6 +135,7 @@ public static Dictionary<string, double[]> ConvertToDictionaryOfSummaryIndices(L
                 { "AvgSnrOfActiveFrames", summaryIndices.Select(x => x.AvgSnrOfActiveFrames).ToArray() },
                 { "Activity", summaryIndices.Select(x => x.Activity).ToArray() },
                 { "EventsPerSecond", summaryIndices.Select(x => x.EventsPerSecond).ToArray() },
+                { "SpectralCentroid", summaryIndices.Select(x => x.SpectralCentroid).ToArray() },
                 { "HighFreqCover", summaryIndices.Select(x => x.HighFreqCover).ToArray() },
                 { "MidFreqCover", summaryIndices.Select(x => x.MidFreqCover).ToArray() },
                 { "LowFreqCover", summaryIndices.Select(x => x.LowFreqCover).ToArray() },
@@ -174,6 +175,8 @@ public static Dictionary<string, double[]> ConvertToDictionaryOfSummaryIndices(L
 
         public double EventsPerSecond { get; set; }
 
+        public double SpectralCentroid { get; set; }
+
         public double HighFreqCover { get; set; }
 
         public double MidFreqCover { get; set; }
diff --git a/tests/Acoustics.Test/AudioAnalysisTools/Indices/IndexCalculateTest.cs b/tests/Acoustics.Test/AudioAnalysisTools/Indices/IndexCalculateTest.cs
index 65424cf75..f6e02e4ec 100644
--- a/tests/Acoustics.Test/AudioAnalysisTools/Indices/IndexCalculateTest.cs
+++ b/tests/Acoustics.Test/AudioAnalysisTools/Indices/IndexCalculateTest.cs
@@ -90,6 +90,7 @@ public void TestOfSummaryIndices()
             Assert.AreEqual(0.260999, summaryIndices.EntropyOfPeaksSpectrum, AllowedDelta);
             Assert.AreEqual(0.522080, summaryIndices.EntropyOfVarianceSpectrum, AllowedDelta);
             Assert.AreEqual(2.0, summaryIndices.EventsPerSecond, AllowedDelta);
+            Assert.AreEqual(0.467151, summaryIndices.SpectralCentroid, AllowedDelta);
             Assert.AreEqual(0.140306, summaryIndices.HighFreqCover, AllowedDelta);
             Assert.AreEqual(0.137873, summaryIndices.MidFreqCover, AllowedDelta);
             Assert.AreEqual(0.055341, summaryIndices.LowFreqCover, AllowedDelta);