The glass transition temperature (T-g(onset)) and super-cooled liquid region (Delta T-x) of Zr55Cu30Ni5Al10, metallic glass ribbon and bulk glassy plate have been measured using conventional and step-scan modulated temperature differential scanning calorimeter (MTDSC). A wide variation of T-g(onset)(+/- 14.8 K) and Delta T-x (+/- 18.5 K) have been estimated using conventional DSC at heating rates of 5-400 K/min in the present study as well the data reported in the literature. We report that T-g(onset) can be precisely (+/- 1.3 K) measured using step-scan MTDSC from the reversible heat flow curve, which excludes the structural relaxation near to glass transition.