Infrared/mass spectroscopy-temperature programmed desorption of ammonia experiment on an SSZ-35 zeolite was measured to characterize the acidity. Two kinds of the Bronsted acid site were detected at 3,622 and 3,505 cm(-1); these concentrations were nearly the same, and the strengths a dagger H were 129 and 117 kJ mol(-1), respectively. These Bronsted hydroxyls were identified to be located in the 10-ring and 5-ring in the STF cage, respectively. These measured strengths were supported well by the DFT calculation.