This work carried out a study on the role of heat source/sink on transient electromagnetohydrodynamics (EMHD) free (natural) convection flow in a vertical micro-channel with electroosmotic effect. The governing energy and momentum equations are converted from partial differential equation (PDE) into ordinary differential equation (ODE) using Laplace transformation technique in order to obtain fluid temperature and velocity in Laplace domain. The Riemann sum approximation method was applied for arriving at the semi-analytical solutions of the temperature distribution and velocity profile. Hence a MATLAB program was coded to study the influence of Prandlt number (Pr), Hartmann number (Ha), electric field strengths on x and z directions (Ex and Sz) and Grashoff number (Gr) on fluid velocity, temperature, skin-friction and mass flow in terms of line graphs. Result shows that the role of heat source/sink parameter has significant impact in the temperature distribution and velocity of the flow. Finally, it is also observed that the governing parameters contribute to the flow formation.