The present analysis deals with the numerical investigation of an unsteady laminar free convective flow of a viscous, incompressible, dissipative, electrically conducting, optically thin and chemically reacting fluid past a moving semi-infinite vertical cylinder embedded in a porous medium. The problem has been governed by a system of coupled nonlinear boundary layer equations with appropriate initial and boundary conditions. These governing equations have been reduced to a non-dimensional form and have been solved numerically using Crank-Nicholson implicit finite difference method, which is unconditionally stable and convergent. The influence of physical parameters such as Prandtl number, Schmidt number, Eckert number, Grashof number for heat transfer, Grashof number for mass transfer, permeability parameter, magnetic parameter, radiation parameter and chemical reaction parameter on velocity profiles, temperature profiles, concentration profiles, local skin-friction coefficient, mean skin-friction coefficient, local Nusselt number, mean Nusselt number, local Sherwood number and mean Sherwood number have been shown graphically. An increase in the value of Eckert number increases the velocity and temperature. Also, the rate of heat transfer and mass transfer gets enhanced for decreasing values of the Eckert number. © 2018 National Institute of Science Communication and Information Resources (NISCAIR). All Rights Reserved.