Reliability and safety of technical equipment has an important role in engineering practice. Determining of reliability of complicated technical equipment requires complex analysis and thorough preparation of inputs which means processing of great volume of information. On the basis of available information about operation and records about character of failures of observed equipment, it is possible by applying proper reliability model, to describe mathematical functions of particular reliability indicators in dependence on their operation time. The aim of the paper is to determine empirical reliability model of cooling unit of electro-erosion machine AgieCut 270HSS on analysis of its failures which are registered in the equipment database.