diff --git a/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs b/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs
index b729b28..c528079 100644
--- a/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs
+++ b/ClosedXML/Excel/CalcEngine/Functions/MathTrig.cs
@@ -66,6 +66,7 @@
             ce.RegisterFunction("ROUNDDOWN", 2, RoundDown);
             ce.RegisterFunction("ROUNDUP", 1, 2, RoundUp);
             ce.RegisterFunction("SEC", 1, Sec);
+            ce.RegisterFunction("SECH", 1, Sech);
             ce.RegisterFunction("SERIESSUM", 4, SeriesSum);
             ce.RegisterFunction("SIGN", 1, Sign);
             ce.RegisterFunction("SIN", 1, Sin);
@@ -751,6 +752,11 @@
                 throw new CellValueException();
         }
 
+        private static object Sech(List<Expression> p)
+        {
+            return 1.0 / Math.Cosh(p[0]);
+        }
+
         private static object SeriesSum(List<Expression> p)
         {
             var x = (Double)p[0];
diff --git a/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs b/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs
index 51c4207..5d258b4 100644
--- a/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs
+++ b/ClosedXML_Tests/Excel/CalcEngine/MathTrigTests.cs
@@ -404,6 +404,32 @@
                     @"SEC(number)")));
         }
 
+        [TestCase(-9, 0.00024682)]
+        [TestCase(-8, 0.000670925)]
+        [TestCase(-7, 0.001823762)]
+        [TestCase(-6, 0.004957474)]
+        [TestCase(-5, 0.013475282)]
+        [TestCase(-4, 0.036618993)]
+        [TestCase(-3, 0.099327927)]
+        [TestCase(-2, 0.265802229)]
+        [TestCase(-1, 0.648054274)]
+        [TestCase(0, 1)]
+        public void Sech_ReturnsCorrectNumber(double input, double expectedOutput)
+        {
+            double result = (double)XLWorkbook.EvaluateExpr(
+                string.Format(
+                    @"SECH({0})",
+                    input.ToString(CultureInfo.InvariantCulture)));
+            Assert.AreEqual(expectedOutput, result, 0.00001);
+
+            // as the secant is symmetric for positive and negative numbers, let's assert twice:
+            double resultForNegative = (double)XLWorkbook.EvaluateExpr(
+                string.Format(
+                    @"SECH({0})",
+                    (-input).ToString(CultureInfo.InvariantCulture)));
+            Assert.AreEqual(expectedOutput, resultForNegative, 0.00001);
+        }
+
         /// <summary>
         /// refers to Example 1 from the Excel documentation,
         /// <see cref="https://support.office.com/en-us/article/SUMIF-function-169b8c99-c05c-4483-a712-1697a653039b?ui=en-US&amp;rs=en-US&amp;ad=US"/>