The five kinds of ferroelectric z-cut LiNbO3 crystals with different thicknesses of 0.3, 0.5, 1.0, 2.0, and 2.2 mm were employed to reveal the effects of frequency in thickness extension mode resonance oscillation (TERO) of acoustic waves on the catalytic properties of a 100 nm thick Ag film deposited onto the crystals. The different thicknesses of the crystals provided 11.2, 7.3, 3.6, 1.8, and 1.6 MHz as the primary resonance frequency, respectively. In ethanol decomposition producing ethylene and acetaldehyde, the characteristics of the TERO that caused significant increases in catalytic activity for ethylene production were observed for the five frequencies, but the extent of activity increments depended on the frequency: a maximum appeared at a medium frequency of 7.3 MHz. Remarkably large decreases in the activation energy for ethylene production occurred with 1.6-1.8 MHz, compared to those of the rest of the frequencies. Laser Doppler measurements showed the different distributions of lattice displacement among the five frequencies. The frequency dependence of catalytic activity enhancement was associated with both the magnitudes of lattice displacement and the density of sites causing lattice displacement. Markedly large distortion due to lattice displacement was observed for 1.6-1.8 MHz, compared to the high frequencies, and is considered to be responsible for large activation energy decreases with the lower frequency. The frequency effects of different crystal thicknesses on catalytic behaviour are discussed.