The large synthesis of graphene films by chemical vapor deposition (CVD) is expected to enable various applications. However, the transfer process of graphene from metal to dielectric substrate becomes a practical limitation in CVD method because of various chemical and mechanical stresses. In this paper, we have studied the critical factor of degradation and thereby to improve the electrical performance of graphene by CVD. It has been found that O=C-OH bonding is related to mobility degradation and doping effect. The removal of O=C-OH improves the carrier mobility by 30%. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.101204jes] All rights reserved.