This paper discusses the rationale and key results of the Comparative Quantitative Risk Estimation of Hydrogen and CNG Refuelling Options project conducted within the Canadian Hydrogen Safety Program for the Codes & Standards Working Group of the Canadian Transportation Fuel Cell Alliance. The project's objectives are tightly linked with the content of the IEA Task 19 Hydrogen Safety. Three compressed hydrogen refuelling options based respectively on tube trailer delivery, on-site water electrolysis and on-site SMR reforming were compared with a conventional CNG refuelling of equal refuelling capacity to provide an equivalent travel mileage of respectively hydrogen (FC) and CNG (ICE) vehicles. Detailed comparative risk analysis included CFD modeling of concentration envelopes resulting from various release scenarios, calculation of thermal effects for horizontal jets and vertical flares, extensive use of fault and event trees to determine frequencies and probabilities of events and, finally, risk estimation for selected locations around key equipment components. Comparison of qualitative assessment of the same options with quantitative results is also discussed.