This paper describes an algorithm that determines the optimal application and coordination of over current protective devices such as fuses, rec1osers, and sectionalisers in distribution networks. The priority is given to providing all main feeders and the laterals with rec10ser protection, while considering security and selectivity of the protection system. In order to achieve these, first the rec10sers are located, then for protection of the laterals suitable fuses are selected based on coordination with the back-up rec1osers. At this stage also the time settings of reclosers are chosen. If, for a lateral, it is not possible to find a suitable fuse from the available fuse range, then a sectionaliser would be required instead. Based on the proposed algorithm, a software program with graphic interface and user friendly features has been developed to assist coordination of over current protection devices in a distribution network. The software has been tested on an Iranian 20kV network and the results presented show the effectiveness of the algorithm.