This study investigates the temperature distribution of a compacted graphite iron (CGI) workpiece in minimum quantity lubrication (MQL) deep-hole drilling. The temperature distribution in the workpiece is predicted using the finite element method, in which the heat flux loads on the chisel and the cutting lip applied to the finite element model are determined using analytical equations. Additionally, heat flux loads on the margin and the heat convection coefficient of the air oil mixture are considered and calculated using the inverse heat transfer method. The inverse method is validated experimentally, and the results demonstrate good agreement with the experimental temperature measurements. The importance of drilling time was demonstrated on the temperature distribution. The maximum temperature was observed on the chisel edge near the center of the hole instead of the outer surface of the hole. (C) 2017 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.