So you have a .NET dll and you want to know the platform it is built for. That is, you want to check whether the .NET dll was targeted for either x86 (32 Bit only) x64 (64 Bit only) Any CPU (both 32 and 64 bit) The easiest way to do this is to use corflags.exe which is supplied with the Microsoft Windows SDK. You can get the Windows 7 SDK from here http://www.microsoft.com/en-us/download/details.aspx?id=8279#overview Command Line to determine platform 1. Locate where CorFlags.exe is. Generally this would be under <ProgramFiles>\Microsoft SDKs\Windows\<version>\Bin\CorFlags.exe 2. Run CorFlags.exe <Full_Path_To_Assembly> . E.g. CorFlags.exe c:\test\test.dll 3. You will see an output like the following S:\r862\sp1\work\pcdm\std\cms>corflags c:\test\test.dll Microsoft (R) .NET Framework CorFlags Conversion Tool. Version 3.5.21022.8 Copyright (c) Microsoft Corporation. All rights reserved. Version : v2.0.50727...