This research focuses on the experimental work performed on AISI D2 steel having a hardness of 55 HRC. Hard turning experiments were conducted based on Taguchi's L27 orthogonal array by considering various machining parameters, tool geometry, cutting tool material and cutting conditions. Altogether eight process variables are used and three different levels are considered for all the variables involved in the experimentation. In general, hard turning process is highly complex and its complexity further increases as more number of operating variables are taken into account. In such a complex situation selecting the optimum cutting conditions for an favorable response in terms of surface finish, tool life, cutting tool temperature and metal removal rate is very difficult. Therefore an attempt is being made to determine the optimum set of process variables using an approach which combines orthogonal array design of experiments and grey relational analysis. Optimal values of all the eight machining variables were determined by the grey relational grade obtained from the grey relational analysis for multi-performance characteristics. © 2017 Elsevier Ltd.