diff --git a/components/fpspreadsheet/examples/other/conditional_formatting/demo_conditional_formatting.pas b/components/fpspreadsheet/examples/other/conditional_formatting/demo_conditional_formatting.pas
index b5fb03865..fda7367fa 100644
--- a/components/fpspreadsheet/examples/other/conditional_formatting/demo_conditional_formatting.pas
+++ b/components/fpspreadsheet/examples/other/conditional_formatting/demo_conditional_formatting.pas
@@ -39,6 +39,14 @@ begin
     // Use the format as conditional format of A1:A6 when cells are equal to 3.
     sh.WriteConditionalCellFormat(Range(0, 0, 5, 0), cfcEqual, 3.0, fmtIdx);
 
+
+    sh.WriteNumber(0, 2, 10.0);
+    sh.WriteNumber(1, 2, 20.0);
+    sh.WriteNumber(2, 2, 15.0);
+    sh.WriteNumber(3, 2, 11.0);
+    sh.WriteNumber(4, 2, 19.0);
+    sh.WriteConditionalCellFormat(Range(0, 2, 4, 2), cfcBelowEqualAverage, fmtIdx);
+
     wb.WriteToFile('test.xlsx', true);
   finally
     wb.Free;
diff --git a/components/fpspreadsheet/source/common/fpsconditionalformat.pas b/components/fpspreadsheet/source/common/fpsconditionalformat.pas
index 050aa2aca..430b37cdc 100644
--- a/components/fpspreadsheet/source/common/fpsconditionalformat.pas
+++ b/components/fpspreadsheet/source/common/fpsconditionalformat.pas
@@ -18,7 +18,7 @@ type
     cfcEqual, cfcNotEqual,
     cfcGreaterThan, cfcLessThan, cfcGreaterEqual, cfcLessEqual,
     cfcBetween, cfcNotBetween,
-    cfcAboveAverage, cfcBelowAverage,
+    cfcAboveAverage, cfcBelowAverage, cfcAboveEqualAverage, cfcBelowEqualAverage,
     cfcBeginsWidth, cfcEndsWith,
     cfcDuplicate, cfcUnique,
     cfcContainsText, cfcNotContaisText,
diff --git a/components/fpspreadsheet/source/common/xlsxooxml.pas b/components/fpspreadsheet/source/common/xlsxooxml.pas
index e4476ff0c..b085c33da 100644
--- a/components/fpspreadsheet/source/common/xlsxooxml.pas
+++ b/components/fpspreadsheet/source/common/xlsxooxml.pas
@@ -3345,25 +3345,48 @@ const
     ('equal', 'notEqual', 'greaterThan', 'lessThan', 'greaterThanOrEqual', 'lessThanOrEqual');
   OPERATOR_NAMES_2: array[cfcBetween..cfcNotBetween] of String =
     ('between', 'notBetween');
+var
+  fmtID: Integer;
+  aveStr, stdDevStr, eqAveStr: String;
 begin
+  fmtID := 0;   // to do: determine dxfId !
+
   case ARule.Condition of
     cfcEqual..cfcLessEqual:
       AppendToStream(AStream, Format(
-        '<cfRule type="cellIs" dxfId="0" priority="%d" operator="%s">' +
+        '<cfRule type="cellIs" dxfId="%d" priority="%d" operator="%s">' +
           '<formula>%s</formula>'+
         '</cfRule>', [
-        APriority, OPERATOR_NAMES_1[ARule.Condition], ARule.Operand1
+        fmtID, APriority, OPERATOR_NAMES_1[ARule.Condition], ARule.Operand1
       ]));
 
     cfcBetween, cfcNotBetween:
       AppendToStream(AStream, Format(
-        '<cfRule type="cellIs" dxfId="0" priority="%d" operator="%s">' +
+        '<cfRule type="cellIs" dxfId="%d" priority="%d" operator="%s">' +
           '<formula>%s</formula>'+
           '<formula>%s</formula>'+
         '</cfRule>', [
-        APriority, OPERATOR_NAMES_1[ARule.Condition], ARule.Operand1, ARule.Operand2
+        fmtId, APriority, OPERATOR_NAMES_1[ARule.Condition], ARule.Operand1, ARule.Operand2
       ]));
 
+    cfcAboveAverage..cfcBelowEqualAverage:
+      begin
+        if (ARule.Condition in [cfcAboveAverage, cfcAboveEqualAverage]) then
+          aveStr := ''
+        else
+          aveStr := ' aboveAverage="0"';
+        if (ARule.Condition in [cfcAboveEqualAverage, cfcBelowEqualAverage]) then
+          eqAveStr := ' equalAverage="1"'
+        else
+          eqAveStr := '';
+        if (ARule.Operand1 = varNull) or (ARule.Operand1 = 0) then
+          stdDevStr := ''
+        else
+          stdDevStr := Format(' stdDev="%d"', [ARule.Operand1]);
+        AppendToStream(AStream, Format(
+          '<cfRule type="aboveAverage" dxfId="%d" priority="%d"%s%s%s />',
+            [fmtId, APriority, aveStr, stdDevStr, eqAveStr]));
+      end;
   else
     FWorkbook.AddErrorMsg('ConditionalFormat operator not supported.');
   end;