The first six production aircraft were delivered to the 6th Fighter Regiment of the VVKJ, based at Zemun, in early 1939. The pilots subjected them to considerable additional testing, before they entered normal service around mid-year. The remaining six entered service during the remainder of 1939. The aircraft were delivered without radios or armament, which were fitted in VVKJ workshops. In October 1939, the IK-2s were transferred to the 4th Fighter Regiment in Zagreb until licence-built Hawker Hurricanes were delivered from Zemun, after which the IK-2s were to be transferred to the 5th Fighter Regiment in Niš. By the end of 1940, all the production IK-2s were concentrated in the 107th Fighter Squadron of the 34th Fighter Group, which consisted solely of IK-2s. This was only an interim allocation, as the other squadron of the group was equipped with Hurricanes, and as soon as the 107th Fighter Squadron could be equipped with Hurricanes, the IK-2s were to move to the 5th Fighter Regiment. The threat of war overtook this planned deployment, and on 13 March 1941, the IK-2s of the 107th Fighter Squadron were moved to Bosanski Aleksandrovac near Banja Luka, under the command of "Kapetan" Zarko Vukajlović.