This technical report describes a test procedure to measure the pa rtial discharge inception voltage (PDIV). It is one of a group of methods which have been recently developed to describe the behaviour of insulating liquids when subjected to high electrical stress. The method is applicable to all types of insulating liquids used in medium and high voltage equipment. Nevertheless the equipment described in this repo rt may not be adapted to liquids with values of PDIV greater than 70 kV (see annex A). Complementary information may be obtained by the gassing properties (IEC 628) and the lightning impulse breakdown voltage (IEC 897) in addition to the widely used measurement of electric strength (IEC 156).