A series of 10 reagents of known chemical structure, synthesized or obtained commercially, were evaluated for their ability to remove pyritic sulfur and ash from ultrafine coal by flotation processes. A correlation was made between the structure of these reagents and their coal cleaning effectiveness and efficiency, i.e., dosage versus weight and energy recovery, and ash and pyrite rejection, for two ultrafine samples, the Illinois No. 5 (hva) and Illinois No. 2 (hvc) coals. Within the series of structurally related surfactants, molecular size, symmetry, and geometry were found to be influential in determining coal cleanability. In general, thecis-1,2-dialkylethenesulfonate salts were more effective than the commercial surfactants which included an alkanesulfate salt, an alpha-olefin sulfonate salt, polyetheralkanesulfonate and sulfate salts, and some alcohols. In some cases, the dosage required to produce equivalent energy recoveries from the, synthesizedcis-1,2-dialkylethenesulfonate salt reagents was only one-third that of the commercial surfactants and one-seventh that of the alcohol frother MIBC.