Possibility of the Maillard reaction to take place in the gaseous phase in the interstellar medium was investigated by using Density Functional Theory (DFT) computations. Cyclic ribose (c-Rib)/open-chain ribose (c-Rib) and glycine were taken as the model. Mechanisms have been proposed, and possibility of the formation of different compounds have been evaluated through calculating the Gibb’s free energy changes for different steps of the reaction by following the total mass balance. The result reveals that both c-Rib and Rib can participate in the reaction, and c-Rib is more efficient than Rib. The reactions under basic and neutral conditions are supposed to be the first and second most favourable. Acidic conditions and the isoelectric point of glycine were unfeasible for the reaction. The kinetics of the mechanics are briefly addressed in this work.