The denaturation of glucose oxidase has been studied as a function of dodecyl trimethyl ammonium bromide (DTAB) concentration at temperatures between 25 and 65-degrees-C, with 2.5 mM phosphate buffer and pH 6.4. DTAB was found to be very effective in denaturing glucose oxidase, normally resistent to other denaturing agents. At 55-degrees-C, the enzyme is expected to have minimum stability in the hydrocarbon environment provided by the detergent. In an otherwise identical situation, when water surrounds the protein, maximum stability is suggested. These predictions are made using the Gibbs free energies of the transition in water DELTAG(D)(H2O), and in a hydrophobic environment DELTAG(D)(hc). The values of DELTAG(D)(H2O) and DELTAG(D)(hc) were 26.84 and -180.2 kJ mol-1, respectively.