In this work, mathematical models were developed to simulate the temperature distribution in two flute and four flute end mills during slotting operations. The Differential equation obtained by modelling the physics of the machining process, subject to appropriate boundary conditions based on energy interactions at the tool boundary, was solved by finite difference method implemented in MATLAB^TM. Descriptive geometric equations were also developed to define the boundary of the tool. Temperature distribution results were obtained typical of a High Speed Steel tool machining a mild steel workpiece subject to variations in machining parameters such as Tool diameter of 25mm, depth of cut of 2mm, Tool Feed of 0.17mm/tooth, Tool Speed of 860 rpm, Tool material conductivity of 40W/m.K, Tool specific heat capacity of 475J/kg.K, Tool density of 8150kg/m³, Specific energy of Tool-workpiece material pair of 4 W.s/mm³.