Ignition delay times of C1-C4 alkanes (methane, ethane, propane, and n-butane) diluted with argon were respectively measured behind reflected shock waves at the same equivalence ratio (phi = 1.0) and different pressures (1.2 and 5.3 atm) and temperatures (1100-2100 K). A same argon-dilution ratio was employed to obtain a reasonable comparison. First, attention was paid on the specific experimental conditions when compared to previous data. Subsequently, two widely used models, USC 2.0 and NUI C4, were used and validated against the experimental data. It was observed that methane and ethane respectively have the longest and the shortest ignition delay times while propane and n-butane show the intermediate values. Both models yield fairly good agreement with the ignition data of C1-C4 alkanes, except the poor prediction of ethane by the USC 2.0 model. Finally, reaction pathway and sensitivity analysis were performed to ascertain the controlling steps during the ignition of ethane in the USC 2.0 model.