Research was conducted in the greenhouse and growth chambers to determine the effect of selected humectants on sulfosulfuron {1-(4,6-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonyl-imidazo[1,2-a]pyridine-3-yl)] sulfonylurea}and glyphosate {N-(phosphonomethyl)glycine} efficacy and sulfosulfuron spray deposit characteristics. Humectants were glycerol, sorbitol, ethylene glycol, propylene glycol, various polyethylene glycols, sodium lactate, and calcium nitrate. Sulfosulfuron was applied to green foxtail and glyphosate to wheat, with and without nonionic surfactants, and with and without humectant in distilled water. None of the humectants substantially increased glyphosate efficacy, and sodium lactate and calcium nitrate were antagonistic. In the presence of nonionic surfactant, sodium lactate and calcium nitrate caused the greatest increase in sulfosulfuron efficacy and overcame the reduced sulfosulfuron efficacy associated with low humidity. Sodium lactate and calcium nitrate enhanced sulfosulfuron efficacy regardless of spray mixture pH, but the increase appeared greater at low pH (4.3–5) than at high pH (7.7–8.2). Scanning electron micrographs showed that spray deposits at low pH contained dry crystals, presumably sulfosulfuron. Sodium lactate gave a liquid-appearing (presumably water) spray deposit. Water retained in sulfosulfuron spray mixture deposits measured on watch glasses was greater with calcium nitrate and sodium lactate than with glycerol, sorbitol, propylene glycol or polyethylene glycol humectants. These data demonstrate the potential for enhancing efficacy of sulfosulfuron by using selected humectants as components of an adjuvant.