Polydiphenylamine and zeolite Y composite were fabricated and tested for the ability to detect the halogenated solvent vapors; dichloromethane, 1,2-dichloroethane, and chloroform. To enhance the sensing properties of the composites, zeolite Y was modified by the dealumination process. The sensitivity of the composites towards the halogenated solvents was examined under the effects of acid treatment time, zeolite content, temporal response, and cyclic response. The resultant dealuminated zeolite Y showed a higher sensitivity when exposed to solvents than the pristine zeolite. An acid treatment time of 12 h provided the highest sensitivity. Sensitivity of the composites towards dichloromethane was higher than those of 1,2-dichloroethane, and chloroform, respectively. The optimal dealuminated zeolite content in the composites was 30 vol.%.