ABSTRACT Although the potential of electric vehicles (EV) has captured a lot of attention lately, there are barriers to overcome before EVs become dominant vehicles on the road. A substantial part of the EV powertrain is the battery cell. The cells are usually connected in series; failure of a single cell can deactivate an entire module. Hence, understanding the cell treatment helps to predict and improve the battery performance. In order to achieve the optimum performance, the battery must be regulated to operate in the desired operating temperature range, and uneven temperature distributions must be reduced. This paper focuses on the thermal behavior of the EV battery cell during charge and discharge state. A numerical model of a Lithium-Ion battery is developed to study the temperature effect in cells designed for EV propulsion. The model is based on the first principles, where the energy equation is coupled with electrochemical kinetic and transfer equations. The electrolyte conductivity and salt diffusivity, and negative electrode diffusivity are considered as temperature dependent parameters, and positive/negative electrode equilibrium potentials are considered as state of charge dependent parameters. The model predicts the heat generation rate in the cell through different state of charge and discharge rates. Furthermore, effects of various operating temperatures on the performance of the cell are discussed.