Convert.ToBase64String converts 8-bit unsigned integers to string encoded with base-64 digits.
Class Sample Public Shared Sub Main() Dim inFile As System.IO.FileStream Dim binaryData() As Byte inFile = New System.IO.FileStream("c:\\a.txt", System.IO.FileMode.Open, System.IO.FileAccess.Read) ReDim binaryData(inFile.Length) Dim bytesRead As Long = inFile.Read(binaryData, 0, inFile.Length) inFile.Close() Dim base64String As String base64String = System.Convert.ToBase64String(binaryData, 0, binaryData.Length) Dim outFile As System.IO.StreamWriter outFile = New System.IO.StreamWriter("c:\\b.txt", False, System.Text.Encoding.ASCII) outFile.Write(base64String) outFile.Close() End Sub End Class