The dual fuel engine is a means for utilizing gaseous fuel resources efficiently in diesel engines after appropriate conversion. These converted engines can provide an effective method for producing power while reducing exhaust emissions, especially exhaust particulates and oxides of nitrogen. More efficient and increased power output relative to the corresponding diesel operation can be achieved with dual fuel engines at relatively high load. The light load performance, especially with high gas to diesel fuel ratios, remains relatively inferior.Poor fuel utilization efficiencies and high unburnt hydrocarbons and carbon monoxide exhaust concentrations are readily encountered at light loads. This trend has necessitated usually the resorting back to diesel operation at idling and very light load conditions. The paper describes the combustion phenomena that bring about these limitations at light load. It then sets out some guidelines that can be followed to permit improved performance and exhaust emissions of diesel engines converted to dual fuel operation when idling and at light load.