This paper proposes a numerically simple physics based optimization (Met Heuristic) method to determine parameters of Proton Exchange Member Fuel cell (PEMFC) .A cell stack of series connected PEMFC to meet the required electrical power ratings is the usual arrangement .Each cell being operated at various operating temperatures provide individual terminal voltages .The terminal voltage measurements are made for n number of series connected individual cells. An objective function is constructed as sum squared error of voltages measured practically with that available by model upon cell parameter estimates. The obtained mathematical model after minimizing the objective function can be integrated for electrical simulation purpose of Electrical Vehicles and smart Grid co –simulation studies. The objective function being non –convex has multiple minima and escaping without being stuck in local minima is a challenge to any Met Heuristic method. Most of Met Heuristic methods are tuning factor dependent while the proposed method in this paper is numerically simple and practical, the proposed method is tested for cell stack of 35 cells and results are also compared with other algorithms and an electrical model circuit is obtained.