By use of trace amounts of the electroactive probes and low supporting electrolyte concentrations, 1.5-order differential electroanalysis is used as an effective method for investigating the physicochemical properties of aqueous Triton X-100 solutions. The diffusion coefficients of probes in Triton X-100 microemulsion microenvironment were measured. The phase inversion from water-in-oil to oil-in-water microemulsions in the Triton X-100/C6H4(CH3)(2)/H2O system over the entire single-phase microemulsion region was examined by 1.5-order differential electroanalysis. The results were found to be in agreement with the results of conductivity measurements.