A two-component liquid reagent and process is provided for detecting the presence of furfural in petroleum products. The reagent comprises the following two components which are stored separately from each other and are combined prior to admixture with the petroleum product:First componentfrom about 15 to about 22 percent of a primary amine selected from the group consisting of aniline, meta aminophenol, para anisidine, meta toluidine and para toluidine;from about 35 to 45 percent of diethylene glycol;from about 35 to about 45 percent of ethanol; andfrom about 1 to 2 percent of an antioxidant;Second Componentfrom about 18 to about 25 percent of an acid selected from the group consisting of citric acid, lactic acid, formic acid and phosphoric acid;from about 35 to about 45 percent of diethylene glycol; andfrom about 35 to 45 percent of ethanol,with the proviso that when in the first component the amine is aniline then in the second component the acid is selected from the group consisting of citric acid, lactic acid and formic acid.The process comprises combining the two separate components of the liquid reagent with each other prior to use, admixing the combined components with a petroleum product containing furfural, shaking the resultant mixture, allowing the mixture to separate and observing a red color characteristic of furfural in the lower layer.Alternately, the process may be carried out by combining the second component of the two-component liquid reagent with the petroleum product, followed by admixture with the first component to obtain two separate layers in which the red color characteristic of furfural is observed in the lower layer.