We report ion energy distributions, relative ion intensities, and absolute total ion current densities at the grounded electrode of an inductively coupled Gaseous Electronics Conference radio-frequency reference cell for discharges generated in pure CF4, and in CF4:Ar and CF4:O-2:Ar mixtures. Abundant ionic species, including secondary ions such as CO+ and COF+, were observed and their implications are discussed. [S0734-2101(99)03204-2].