The aim of this study is to model and optimize the cutting conditions for the cutting force (F-c) and average surface roughness (R-a) that result from the machining of high-alloy white cast iron (Ni-Hard). The hard turning experiments were carried out on a CNC lathe with ceramic and CBN inserts. Cutting tool material, cutting speed, feed rate and depth of cut were chosen as the cutting conditions (control factors). Taguchi's L-18 orthogonal array was used for design of experiment. Optimum levels of the cutting conditions were determined using signal-to-noise (S/N) ratio, which was calculated for machining output variables (F-c and R-a) according to the the-smaller-the-better' approach. The effects of the cutting conditions on machining output variables were evaluated by the analysis of variance. The analysis of variance results showed that the depth of cut and feed rate were the most significant factors on F-c and R-a, respectively. Besides, the optimal cutting conditions for main cutting force and surface roughness were found at the different levels.