Abstract: The invention provides a method of testing sour natural gas by a) removing H2S from the gas stream, b) converting H2S to elemental sulfur, and c) recovering elemental sulfur. The invention also provides a substantially mobile system for testing sour natural gas including vehicles allowing the equipment to be operated on surfaces such as the flat beds of trailers. The system features equipment that may be mounted within one or more support structures situated on a mobile vehicle, such as, for instance the flat bed of a trailer. The one or more support structures hold each piece of equipment substantially fixed in place on the vehicles. Each surface such as the flat bed of a trailer may carry one, two or more pieces of equipment. The equipment may include, for instance, an air or oxygen compressor, a knockout vessel, a gas heater, an air heater, a cooler, a molten sulfur separator and a thermal oxidizer.