The paper reports the synthesis of embryonic and highly crystalline ZSM-5 zeolites with SiO2/Al2O3 ratios of 50 to 400, as well as the examination and comparative evaluation of their physicochemical properties by XRD, low-temperature nitrogen adsorption/desorption, ammonia TPD, and TEM methods. The Ni-W sulfide catalysts prepared in situ from the embryonic and highly crystalline ZSM-5 were investigated in a hydrocracking reaction of 1-methylnaphthalene (50 atm H2, 380 degrees C, 5 h). The catalytic systems based on embryonic ZSM-5 were found to promote, to a larger extent, the hydrogenation and migration of the methyl group on the naphthalene ring.