Preparation of ZSM-12 zeolite (MTW structure) functionalized with the organosilane surfactant [3-(trimethoxysilyl)propyl]octadecyldimethylammonium chloride (TPOAC) was performed in a single synthesis step employing hydrothermal crystallization. Investigation was made of the effects of Si/Al and TPOAC/SiO2 ratios on crystallinity, morphology, and catalytic activity. The MTW structure without the presence of TPOAC was obtained using Si/Al ratios ranging from 50 to 120, with values smaller than 50 favoring crystallization of the BEA phase, and values greater than 120 leading to the formation of cristobalite, a crystalline silica phase. For syntheses performed in the presence of TPOAC, an increase in its amount from 3 to 6 % enabled formation of the pure MTW structure, at all Si/Al ratios. The addition of TPOAC led to significant changes in the morphology and hydrophobicity of the zeolite particles. The effect of functionalization with TPOAC on the catalytic performance of the zeolites was evaluated using the Knoevenagel condensation between butyraldehyde and ethyl cyanoacetate as a model reaction. It was found that the presence of TPOAC in the ZSM-12 zeolite substantially increased the catalytic activity. Evaluation was also made of the type of solvent used in the reaction, and high activities were obtained in the presence of polar protic solvents. [GRAPHICS] .