•Grafting methyl on the inner surface to enhance the water tolerance of HY.•Attachment of methyl leads to an enhancement of toluene adsorption capacity.•Outer surface silanization could not reduce the effect of water on toluene adsorption.•The adsorption behavior was investigated by adsorption kinetics and Y-N model. Although Y zeolites are considered as a promising adsorbent for capturing volatile organic compounds (VOCs), its hydrophilic nature causes a significantly decrease in VOCs adsorption performance due to the pervasive water vapor in VOCs streams. Herein, a facile approach is proposed to significantly enhance the hydrophobicity by grafting methyl on the inner surface of Y zeolite. Attachment of methyl to the inner surface leads to a significant reduction in water affinity, resulting in a notable enhancement of toluene adsorption capacity in humid environment. The silanization process and the evolution of silane species are further elucidated through in-situ DRIFTS, NMR and TGA. Adsorption kinetics reveals that inner surface silanization reduces the adsorption rate constant of water by 50 %. However, the outer surface silanization with propyl is ineffective in mitigating the detrimental impact of water on the toluene adsorption. Moreover, Yoon-Nelson (Y-N) model analysis is applied to predict the breakthrough characteristics of fixed-bed adsorption and to evaluate the applicability in actual industry. In this work, this regioselective silanization approach could provide a facile strategy for controlling VOCs in humid environment.