The invention provides a process for the preparation of ethylene glycol and 1,2-propylene glycol from starting material comprising one or more saccharides, by contacting said starting material with hydrogen in a reactor in the presence of a solvent and a catalyst system with catalytic hydrogenation abilities, wherein the process comprises the steps of: i) introducing a first portion of the starting material into the reactor such that the initial concentration of the saccharide in the solvent in the reactor is no more than 2 wt %; ii) allowing at least 90 wt % of the saccharide in the first portion of the starting material to react; iii) subsequently adding further portions of starting material to the reactor over time; and removing reaction product from the reactor.