Abstract: Formation of simple organic species such as glycine in the interstellar medium and transportation to earth via meteorites is considered to be a possible route for ‘Origin of Life’ on earth. Glycine formation has been proposed to occur via two different pathways involving formaldehyde (HCHO) and methanimine (CH 2= NH) as key intermediates. In the second pathway, which is the topic of this paper, CH 2= NH reacts with CO and H 2O forming neutral glycine. In a recent article (Nhlabatsi et al. in Phys. Chem. Chem. Phys. 18:375, 2016), detailed electronic structure calculations were reported for the reaction between CH 2= NH , CO and (H2O)n, n= 1 , 2 , 3 , and 4, forming glycine in the interstellar media. The presence of additional water molecule(s) for this reaction reduces reaction barrier - thus exhibiting a catalytic effect. This effect was described in terms of efficient proton transfer mediated by the additional water molecule through a relay transport mechanism. In the present article, we report ab initio classical trajectory simulations for the interstellar formation of glycine for the above mentioned reaction with n= 1 and 2. The trajectories were generated on-the-fly over a density functional B3LYP/6-31++G(3df,2pd) potential energy surface. Our simulations indicate that the above proposed catalytic effect by the additional water molecule(s) may not be a classical effect. Graphical Abstract: Synopsis: Glycine formation in the interstellar media via the CH 2= NH + CO + H 2O reaction was investigated by classical chemical dynamics simulations. This reaction has a large barrier which reduces in presence of additional water molecules. Our simulations indicate that the proposed catalytic effect by the additional water molecules may not be a classical effect. [Figure not available: see fulltext.]. © 2017, Indian Academy of Sciences.