Corrosion in gas pipelines takes many forms. One of these forms is corrosionin vapor space areas, This paper described results of tests designed to better understand this process in sour gas lines and how to inhibit this corrosion. Corrosion in the vapor space above sour fluidswas found to proceed in an unsteady manner. The presence of liquid hydrocarbon lowered rates, whereas oxygen contamination increased rates. Methanol did not increase uninhibited rates but did diminish inhibitor effectiveness. The most effective inhibitors were found to be blends of imidazolines with light amines at particular ratios. Field confirmation of inhibition was demonstrated.