A 2- unit cold standby system with exponential failure time and general repair time distribution is considered . A quantity of great relevance in the maintenance of equipments in modern business and industrial systems , systems , vzt., profit that system will earn per unit time , has been obtained analytically under unidiscounted and discounted cost structure by superimposing Howard’s reward structure on the semi-Markov generated by the system. Steady – state profit has also been studied for its behaviour for a special case.