Abstract Propene has been oligomerized at high conversion over ZSM-5 zeolite of conventional (spheral aggregate) morphology in a fixed-bed, tubular reactor at 24 bar. Oligomerization at approximately 462K gives dimer, trimer, tetramer, etc. without shape selectivity. Reaction probably occurs on the external surface of the zeolite rather than within the channels. Higher temperatures, particularly when the external surface is poisoned, result in formation of a broader range of hydrocarbons (C 4, C 5, C 6, C 7, etc.), rather than simple oligomers, and shape-selectivity is apparent.