Nanocrystalline MgO doped with potassium metal caused the formation of highly basic sites that are capable of alkene isomerization and alkene alkylation, including the conversion of propylene-ethylene mixtures to pentenes and heptenes. The total number of basic sites closely correlates with the estimated number of ions that exist on edges/corners on the polyhedral crystallites. Only a fraction of these sites are basic enough to cause the alkylation reactions, and these were formed more prevalently on nanocrystalline MgO as compared with microcrystalline MgO. The results represent another example of nanocrystalline materials possessing unique surface chemistry.