Oxalic acid modified H beta (OA-H beta) zeolite is found to have better catalytic performance than H beta zeolite in the Friedel-Crafts hydroxyalkylation of anisole with chloral. This is attributed to the increase of weak and moderately-strong acid sites, caused by oxalic acid modification. Furthermore, it is believed that the carbonaceous deposits on the acid sites and the blockage of the pores, together with poisoning by chlorinated materials, are responsible for the deactivation of OA-H beta zeolite, as indicated by NH3-TPD, BET, SEM, TG and XPS measurement results. Moreover, partial regeneration of OA-H beta zeolite can be achieved via subsequent calcination. Oxalic acid modified H beta zeolite is found to have better catalytic performance than H beta zeolite in the Friedel-Crafts hydroxyalkylation of anisole with chloral. The carbonaceous deposits on the acid sites and the blockage of the pores, together with poisoning by chlorinated materials, are responsible for the deactivation of OA-H beta zeolite.