Magnetohydrodynamics (MHD) is generally concerned with the study of the magnetic properties (behaviour) of electrically conducting fluids (plasmas, liquid metals etc.) moving in an electromagnetic field. The importance of the concept of MHD in various fields such as astrophysics, bio-medical research, missile technology and geophysics motivates the modelling and investigation of MHD flow and transport problems. The role of fluid suction is paramount in laminar flow control and has wide applications in fields such as aeronautical engineering, automobile engineering and rocket science. This fact inspires the study of the effects of fluid suction in flow and transport models. Time dependent flows are widely encountered in engineering applications such as turbines and in physiological studies such as flow of bio-fluid (blood etc.). In the present paper, an attempt has been made to investigate analytically the problem of a time dependent channel flow with heat transfer, where the channel is bounded by two infinite parallel porous walls. The pressure gradient is assumed to be oscillatory in nature. A magnetic field of uniform strength is assumed to be applied normal to the walls. After necessary idealization of the momentum and energy equations, the governing equations of our problem are solved by adopting the regular perturbation technique. The effects of magnetic field, suction velocity, viscous dissipation, Reynolds number, Prandtl number etc. on the flow and heat transfer are studied and demonstrated graphically. It is seen that magnetic field, fluid suction, viscous dissipation, Reynolds number, Prandtl number have a significant effect on the flow and heat transfer characteristic. For instance, the imposition of the magnetic field enhances the rates of heat transfer at the walls and the fluid suction decreases the temperature and aids in laminar flow control