Non-Equilibrium Molecular Dynamics simulations were performed to study thermal rectification effects in monolayer MoS 2 /WS 2 lateral heterostructures. The parameters studied were the system length and the temperature bias ΔΤ. The maximum Thermal Rectification (TR) ratios found are of the order of 30%. The phonon Densities of States (pDOS) in the out-of-equilibrium steady state conditions were also probed, as well as the transmission of acoustic Phonon Wavepackets across the interface. We have found that non-linearities induced by large temperature biases ΔT are necessary for significant rectification ratios η.