The joint pricing and inventory control is known as an efficient supply chain management policy. It is even more prominent when retailers sell deteriorating products in a competitive common market. In this paper, we consider duopoly retailers selling substitutable deteriorating products, and confronting a price-dependent linear demand. Both retailers, simultaneously, determine their price and replenishment cycles to maximize their profit. Using a game theoretic approach, we formulate and analyze the cases with shortages and without shortages. The existence and uniqueness of the Nash equilibrium prices are analytically proved. Then, a solution procedure is outlined to obtain the equilibrium prices and replenishment cycles. Furthermore, the case of a monopolist is investigated in comparison with the duopoly case. Lastly, a numerical study is carried out to examine the effect of competition intensity and other important parameters on the equilibrium quantities. This study provides several interesting insights in pricing and inventory decisions of competing agents. For instance, the results show that while the retailer with bigger market size loses some profits due to competition, the retailer with smaller market size benefits from a limited competition.
