diff --git a/soap/types.go b/soap/types.go
index a2d4a13..abb110a 100644
--- a/soap/types.go
+++ b/soap/types.go
@@ -1,6 +1,7 @@
 package soap
 
 import (
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"regexp"
@@ -396,3 +397,13 @@ func UnmarshalBoolean(s string) (bool, error) {
 	}
 	return false, fmt.Errorf("soap boolean: %q is not a valid boolean value", s)
 }
+
+// MarshalBinBase64 marshals []byte to SOAP "bin.base64" type.
+func MarshalBinBase64(v []byte) (string, error) {
+	return base64.StdEncoding.EncodeToString(v), nil
+}
+
+// UnmarshalBinBase64 unmarshals []byte from the SOAP "bin.base64" type.
+func UnmarshalBinBase64(s string) ([]byte, error) {
+	return base64.StdEncoding.DecodeString(s)
+}
diff --git a/soap/types_test.go b/soap/types_test.go
index 3af92bd..2a48311 100644
--- a/soap/types_test.go
+++ b/soap/types_test.go
@@ -1,6 +1,7 @@
 package soap
 
 import (
+	"bytes"
 	"math"
 	"testing"
 	"time"
@@ -146,6 +147,18 @@ func (v BooleanTest) Equal(result interface{}) bool {
 	return bool(v) == result.(bool)
 }
 
+type BinBase64Test []byte
+
+func (v BinBase64Test) Marshal() (string, error) {
+	return MarshalBinBase64([]byte(v))
+}
+func (v BinBase64Test) Unmarshal(s string) (interface{}, error) {
+	return UnmarshalBinBase64(s)
+}
+func (v BinBase64Test) Equal(result interface{}) bool {
+	return bytes.Equal([]byte(v), result.([]byte))
+}
+
 func Test(t *testing.T) {
 	const time010203 time.Duration = (1*3600 + 2*60 + 3) * time.Second
 	const time0102 time.Duration = (1*3600 + 2*60) * time.Second
@@ -257,6 +270,12 @@ func Test(t *testing.T) {
 		{str: "other", value: BooleanTest(false), noMarshal: true, wantUnmarshalErr: true},
 		{str: "2", value: BooleanTest(false), noMarshal: true, wantUnmarshalErr: true},
 		{str: "-1", value: BooleanTest(false), noMarshal: true, wantUnmarshalErr: true},
+
+		// bin.base64
+		{str: "", value: BinBase64Test{}},
+		{str: "YQ==", value: BinBase64Test("a")},
+		{str: "TG9uZ2VyIFN0cmluZy4=", value: BinBase64Test("Longer String.")},
+		{str: "TG9uZ2VyIEFsaWduZWQu", value: BinBase64Test("Longer Aligned.")},
 	}
 
 	// Generate extra test cases from convTests that implement duper.