Hi, 1. Copy mydll.dll to temp 2. Open Windows Startmenue, type "powershell" open the Windows Powershell or the SharePoint 2010 Administration Shell I completed upto this. from 3rd point onwards i tryed in powershall but i am not able to got that.. 3. Set alias to Gacutil, type: Set-Alias Name:Gacutil -Value "C:\Program Files (x86)\Microsoft SDKs\Windows\v7.0A\bin\gacutil.exe" 4. Add dll to gac, type: Gacutil /i C:\temp\mydll.dll" Thanks, Hemadri.T