This paper presents the inventory model considering inflation under non-deterministic situations, which can be used for arbitrary probability density function (pdf), for the inflation rate. We used two solution methods for determining the optimal ordering policy: (1) classical optimization method and (2) particle swarm optimization (PSO) method with comparing the results. The shortages are allowed and fully backlogged. A constant fraction of the on-hand inventory deteriorates per unit time, as soon as the item is received into inventory. The numerical examples are provided to explore the correctness of theoretical results, which are further clarified through a sensitivity analysis on the parameters of the model.