A series of phenyl functionalized MSU mesoporous molecular sieves were synthesized under neutral condition in the presence of biodegradable non ionic polyethylene oxide(AEO 9). By subsequent sulphonation of the phenyl rings attached to the silica framework, the phenylsulphonic acid functionalized MSU derivatives could be obtained. Their structure and property of the organo modified mesoporous molecular sieves were studied by means of XRD, FT IR, TEM, HRTEM, 13 C MAS NMR, 29 Si MAS NMR, N 2 adsorption/desorption and probe reaction techniques. The results showed that the so produced organo modified mesoporous molecular sieves featured bimodal pore size distribution and the pore channel was similar to those in the \{MSU(worm like)\}. The organo modified mesoporous molecular sieves containing phenylsulphonic acid active sites, used as solid acid catalyst, showed a much higher catalytic activity for the formation of 2,2 pentamethylene 1,3 dioxolane(cyclic ketal) from ethylene glycol and cyclohexanone.[WT5HZ]