Abstract Three kinds of modifications were performed on an offretite type zeolite: 1) Lanthanum exchanges (0.1 and 0.5 La-atom/u.c.), 2) Phosphorous compound impregnation (2.4 wt%), 3) Hydrothermal dealumination and HCl extractions (Al/Si = 0.23 to 0.10). Catalytic studies relative to two reactions, n-hexane cracking and methanol conversion into hydrocarbons, are described in this paper. If improvement of resistance to aging is considered, dealumination of offretite appears to involve the best modification. Results are interpreted in terms of changes of the porous and acidic properties. Lanthanum exchange was observed to decrease mainly the offretite acidity while phosphorous compound impregnation resulted in important pore blocking.