The thermal dehydration of AI(OH)(3), Mg(OH)(2) and the mixed hydroxide (1:1) were investigated, both powder and compact forms using DTA and TGA techniques. Kinetic parameters, such as activation energy, pre-exponential factor and activation entropy were calculated from TG curves. The results obtained showed that the dehydration process inside the pores of AI(OH)(3) appears to be the largest complexity compared to that inside the pores of all other samples (Delta S* = -190.3 JK(-1)mol(-1)). In mixed compacted samples the migration of water molecules from the pores of Mg(OH)(2) to those of Al(OH)(3) takes place. The catalytic activities for conversion of methanol to ether and methane were found to decrease sharply by compaction up to 8 tons inch(-2) beyond which it remains nearly constant up to 20 tons inch(-2). This indicates that compaction hinders the accessible diffusion of the methanol molecules to active sites. The water molecules collected by compaction blocked the active centres participating in the reaction. These sites retain their original activity by evacuation. The most active catalyst was gamma-Al2O3 which gives the lowest negative Delta S* values (-252.5, -143.1 JK(-1)mol(-1)) for ether and methane formation respectively. The activities of gamma-Al2O3-MgO before and after compaction were different, which can be attributed to the difference in the number of acid sites of their catalysts but not in their strengths Delta S* values are not significantly different).