The reforming of methylcyclopentane or ethylcyclopentane over Pt/beta zeolite catalysts of various SiO2/Al2O3 molar ratios has been examined at various H-2 pressures. The balancing of the Bronsted acidity with the Pt loading at an appropriate pressure maximizes the dehydroisomerization of the naphthenes. A maximum aromatic yield occurs for both naphthenes for a catalyst with a Pt (determined by H-2 chemisorption)/Al atoms ratio of about 3 X 10(-2) (SiO2/Al2O3 molar ratio of 130 and a Pt loading of 0.5 wt.-%) and at a pressure of about 800 kPa. The control of the Bronsted acidity via dealumination minimizes coke formation and hydrocracking and results in the preservation of the catalyst activity for many hours-on-stream. The coke was characterized using H-1-NMR, FTIR, and TGA.