How to get type of COM object

Question

Add reference to Microsoft.VisualBasic.dll and then:

Microsoft.VisualBasic.Information.TypeName(someCOMObject)

MSDN reference here.

The accepted answer by Darin requires a dependency to Microsoft.VisualBasic.dll. If you don't want to have that you can use this simple helper class:

public static class TypeInformation
{
    public static string GetTypeName(object comObject)
    {
        var dispatch = comObject as IDispatch;

        if (dispatch == null)
        {
            return null;
        }

        var pTypeInfo = dispatch.GetTypeInfo(0, 1033);

        string pBstrName;
        string pBstrDocString;
        int pdwHelpContext;
        string pBstrHelpFile;
        pTypeInfo.GetDocumentation(
            -1, 
            out pBstrName, 
            out pBstrDocString, 
            out pdwHelpContext, 
            out pBstrHelpFile);

        string str = pBstrName;
        if (str[0] == 95)
        {
            // remove leading '_'
            str = str.Substring(1);
        }

        return str;
    }

    [ComImport]
    [InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
    [Guid("00020400-0000-0000-C000-000000000046")]
    private interface IDispatch
    {
        int GetTypeInfoCount();

        [return: MarshalAs(UnmanagedType.Interface)]
        ITypeInfo GetTypeInfo(
            [In, MarshalAs(UnmanagedType.U4)] int iTInfo,
            [In, MarshalAs(UnmanagedType.U4)] int lcid);

        void GetIDsOfNames(
            [In] ref Guid riid,
            [In, MarshalAs(UnmanagedType.LPArray)] string[] rgszNames,
            [In, MarshalAs(UnmanagedType.U4)] int cNames,
            [In, MarshalAs(UnmanagedType.U4)] int lcid,
            [Out, MarshalAs(UnmanagedType.LPArray)] int[] rgDispId);
    }
}

You've basically figured it out. GetType() on a COM object is going to give you System.__ComObject, and you have to try to cast it to something else to see what the object really is.