A study of the boric acid-glycerin complex was conducted at temperatures of 30, 40, 50, and 60° and the effect of increasing the concentration of glycerin upon the solubility of boric acid was studied. This may then be indicative of the degree of complex formation taking place between these two substances. Concentrations of glycerin varying from 0 to 100% were utilized. The results of these experiments show the relationship between (a) solubility of boric acid and (b) temperature and concentration of glycerin. A phase diagram was constructed at these temperatures showing the quantitative relationship among boric acid; water, and glycerin. From a plot of the log solubility of boric acid versus the reciprocal of absolute temperature, the heat of solution at various concentrations of glycerin was calculated. It was found that the degree of complex formation between boric acid and glycerin increased with an increase in temperature but showed little, if any, increase with an increase in glycerin concentration from 0 to about 40%. However, above this concentration of glycerin, the degree of complex formation, as indicated by the solubility, increased with an increase in concentration of glycerin.