Ignition delay times of CH4/CH3Cl/O-2/Ar mixtures are measured using a shock tube at 1350-1950 K and 4-18 atm. Equivalence ratios of 0.5 and 1 and CH3C1 blending ratios ranging from 0 to 1 are explored. Correlations for the measured delay times are obtained through multiple linear regression. Increasing the blending ratio facilitates ignition, but this effect becomes saturated at a blending ratio of similar to 0.2. Two existing chemical kinetic models for CH4/CH3Cl mixtures are examined against the measurements, and a modified chloromethane-Polimi-kin model incorporating the Aramco 2.0 model is proposed and validated through comparison with these new data. Based on the proposed model, sensitivity analysis, peak concentration analysis, and reaction pathway analysis are carried out to provide further insight into the ignition process of CH4/CH3Cl/O-2/Ar mixtures.