Short-chain oligomers such as dimers and trimers are highly valued products because of their excellent biocompatibility caused by the presence of multi-hydrophilic groups within their structures. Conventionally, oligomers are produced via solvent-free glycerol etherification reactions using a simple heating process. However, the process requires a long reaction time (>7 h). Therefore, this work aims to minimize the reaction time by using microwave irradiation as a heating source and to enhance the yield of dimers and trimers by using a catalyst prepared from clay as an economical material for glycerol etherification. Thus, lithium-intercalated montmorillonite clay (Li/mk-10) was prepared via the wet impregnation method. The maximum 98 glycerol conversion was achieved in 4 h with the maximum dimer yield of 45 in 3 h. © 2020 Japan Institute of Energy. All rights reserved.