The hard turning process has been attracting interest in different industrial sectors for finishing operations of hard materials at its hardened state. Surface roughness is investigated in hard turning of AISI D3 and AISI H13 steels of same hardness 62HRC. In this paper, an attempt has been made to model and predict the surface roughness in hard turning of AISI D3 and AISI H13 hardened steels using Response Surface Methodology (RSM). The combined effects of three machining parameters such as cutting speed, feed rate and depth of cut are investigated for main performance characteristic that is surface roughness. RSM based Central Composite Design (CCD) is applied as an experimental design. Al2O3/TiC mixed ceramic tool with corner radius 0.8 mm is employed to accomplish 20 tests with six center points. The acceptability of the developed models is checked using Analysis of Variance (ANOVA).The combined effects of cutting speed; feed rate and depth of cut are investigated using surface plots.