Organic microporous materials based on spiroketal and spirothioketal polymers were synthesized through 1,3- dioxol-forming polymerization reaction between pentaerythritol or pentaerythritol tetrathiol and different types of cyclohexa- 1,4-dione derivatives.The structure of the prepared polymers was confirmed by NMR spectroscopy and molecular mass measurements.Nitrogen adsorption/desorption isotherms of the prepared polymers show a large amount of nitrogen adsorbed at low relative pressure indicating microporosity.These polymers have Brunauer Emmitt and Teller(BET)surface areas in the range from 492(m~2g~(-1))to 685(m~2g~(-1)).The prepared polymers were found to be useful for pervaporation separation of methanol-toluene mixture with a separation factor up to 12.5 and fluxes,varying between 6.7×10~(-3)kg/(m~2 h)and 13.4×10~(-3)kg/(m~2h). Organic microporous materials based on spiroketal and spirothioketal polymers were synthesized by 1,3- dioxol-forming polymerization reaction between pentaerythritol or pentaerythritol tetrathiol and different types of cyclohexa-1,4-dione derivatives. The structure of the prepared polymers was confirmed by NMR spectroscopy and molecular mass measurements. Nitrogen adsorption / desorption isotherms of the prepared polymers show a large amount of nitrogen adsorbed at low relative pressure indicating microporosity. The polymers have Brunauer Emmitt and Teller (BET) surface areas in the range from 492 (m ~ 2g ~ (-1) to 685 (m ~ 2g -1). The prepared polymers were found to be useful for pervaporation separation of methanol-toluene mixture with a separation factor up to 12.5 and fluxes, varying between 6.7 × 10 ~ (-3) kg / (m ~ 2 h) and 13.4 × 10 ~ (-3) kg / (m ~ 2h), respectively.