This paper deals with an experimental investigation of laser tempering of AISI D2 tool steel. The Nd: YAG laser was used for the tempering. The laser was delivered through a fiber optic cable from the source to the delivery head. The laser delivery head was mounted in a lathe using a special fixture for treating the cylindrical work pieces. The effect of laser parameters such as power and spot size, and machine parameters such as surface speed and feed were studied. The microstructures of the laser tempered samples show tempered white layer and dark heat affected zones in all work pieces. The variation of micro hardness was measured from the top surface of work piece to the depth of heat affected zone and plotted. © 2014 Published by Elsevier Ltd.