A self-consistent, one-dimensional simulator for the physics and chemistry of radio frequency (rf) plasmas was developed and applied for CH4 and CF4. The simulator consists of a fluid model for the discharge physics, a commercial Boltzmann equation solver for calculations of electron energy distribution function (EEDF), a generalized plasma chemistry cone, and an interface module among the three models. The CH4 and CF4 discharges are compared and contrasted : CH4 plasmas are electropositive, with negative ion densities one order of magnitude less than those of electrons, whereas CF4 plasmas are electronegative, with ten times more negative ions than electrons. The high-energy tail of the EEDF in CH4 lies below both the Druyvensteyn and Maxwell distributions, whereas the EEDF high-energy tail in CF4 lies between the two. For CH4, the chemistry model was applied for four species, namely, CH4, CH3, CH2, and H, whereas for CF4, five species were examined, namely CF4, CF3, CF2, CF, and F. The predicted densities and profiles compare favorably with experimental data. Finally, the chemistry results were fed back into the physics model until convergence was obtained.