The counterflow ignition of methane, ethylene and mixtures of methane and hydrogen were investigated computationally and experimentally, with particular interest in the role of radical versus thermal explosions. Simulation with different kinetic mechanisms showed that the ignition response is qualitatively sensitive to the kinetic mechanism adopted, for both methane and ethylene, either exhibiting or not exhibiting two ignition turning points in the S-curves. For the former situations, ignition could take place in a staged manner with increasing temperature of the counterflowing air jet, and the first ignition event is radical induced with negligible heat effect, while the second ignition event requires thermal feedback. Sensitivity and computational singular perturbation (CSP) analysis were performed to identify the dominant reactions in the radical explosion stage, indicating the importance of the HO2 radical in controlling the branching. A preliminary experiment based on luminosity detection however did not register any hysteresis response from the potential first stage ignition. Finally, it was found that a small amount of hydrogen addition to the hydrocarbon mixtures readily induced the first ignition event.