1-D shock wave propagation in RDX crystal is simulated using molecular dynamics (MD) with the ReaxFF potential, a forcefield that can simulate chemical reactions in C,H,N,O systems. High velocity impact simulations in RDX molecular crystal along the X, Y and Z axes have been carried out to (i) obtain the relation between the shock velocity (U s) versus the particle velocity (U p) and (ii) to study the decomposition products of RDX under shock conditions. The U s –U p shows a reasonable match with experiments. It is seen that crystal RDX decomposes only at impact velocities greater than 2.0 kmps and the decomposition products observed favours two of the three different decomposition pathways that have been proposed earlier for RDX.