Electric vehicles have a great potential to decrease the adverse effects of transportation, especially in metropolitan cities. On the other hand, adoption of the electric vehicles requires supporting infrastructure such as charging stations and policies to enhance the transition from conventional gasoline vehicles to electric vehicles. Hence, determining optimal charging station locations is an important task for both having an economically feasible transition and reinforce the market shares of electric vehicles. This paper investigates the optimal locations for charging stations in Istanbul, Turkey. An integer programing model is developed and optimal charging locations in Istanbul is determined for three different market penetration scenarios, namely 10%, 25%, and 50% market penetration.  The results can be useful for policies aiming to enhance use of electric vehicles, thus minimizing the environmental impacts of transportation, as well as fossil fuel dependency.