[en] Parametric decay processes near the ion cyclotron frequency are investigated experimentally and theoretically in multi-ion species plasmas. The relevant theoretical dispersion relation of the parametric coupling is derived, including the ion drift motion. Experiment data obtained in the Princeton L-4 device verifies these theoretical predictions in some detail. In a helium-neon plasma, the relative ion drift motion excites electrostatic ion cyclotron waves (the kinetic ion-ion hybrid mode) when Ω₀ > Ω/sub He/ + Ω/sub Ne/. In a region of large density gradient, the ion drift motion also excites low frequency drift waves when Ω₀ > Ω/sub He/ + Ω/sup */. The experimental data are found to agree well with the theory. The relevance of these processes to ICRF heating of fusion plasmas is pointed out