Abstract: For reasons of sustainability, greenhouse gas emissions, and energy security, it becomes necessary to properly evaluate all of possible options for powering transportation fleet for a particular country. When doing this it is equally important to understand all the costs (economic, social, and environmental) and emissions during the fuel extraction, refining and distribution stages as well as the final combustion stage. All steps in the full pathway contribute to the final economic and environmental profile of any given fuel. The natural gas (NG) family of fuels has to be seriously considered as providing for large-scale transportation. From a combustion point of view, NG derivatives have a lower carbon-to-hydrogen ratio than oil-based fuels and should therefore be cleaner, but the upstream emissions of the fuels need to be properly understood. The supply pathways of gaseous fuels are more diverse than the oil-based fuels pathways, because the sources of gas are varied and can imply substantially different emissions profiles. It is therefore important to understand these various pathways for the country under consideration, so that profiles for each country can be documented and policy formulated accordingly. This preliminary study is conducted based on a life cycle assessment (LCA) approach to evaluate potential sustainability of using gaseous fuels (CNG/LNG) for light commercial and passenger vehicles based on conditions in Australia and Ukraine, which are quite different, taking into account information on the production, distribution and use of gaseous fuel. Data for this study are mostly sourced from published literature. The results of the study reveal a significant opportunity for Australia, as well as for Ukraine to increase sustainability of the transport fleet if it takes gaseous fuels on as major source for transport vehicles.