Raman spectroscopy has been employed to distinguish between the Raman spectrum of pristine hydrogenated diamond like carbon (PHDLC) and that of electrochemically hydrogenated diamond like carbon (ECHDLC). The enhancement of the background photoluminescence (PL) in the Raman spectrum and broadening of PL spectrum of ECHDLC are identified to be due to increase of sp(3) C-H density onto the PHDLC surface, during novel electrochemical process of hydrogenation of sp(2) C=C into sp(3) C-H. (C) 2014 Elsevier B.V. All rights reserved.