The isomerization of styrene oxide has been investigated on mixed oxides obtained by calcination of hydrotalcites, rare earth phosphates and KF supported on alumina. All solids form beta-phenylacetaldehyde. Basic catalysts deactivate rapidly or show a lower selectivity, most probably due to the formation of heavy products by aldolisation. ZnAl catalyst shows a selectivity towards beta-phenylacetaldehyde >98% with no deactivation after 7 h on stream, in a flow gas phase process at 423 K.