Phase diagrams of pseudo-quaternary systems of cetyltrimethylammonium bromide (CTAB)/polyoxyethylene (20) cetyl ether (Brij-58)/water/1-butanol (or 1-pentanol)/n-heptane (or n-decane) at fixed ω (=[water]/[surfactant]) of 55.6 were constructed at different temperatures (293, 303, 313, and 323 K) and different mole fraction compositions of Brij-58 (X Brij-58= 0, 0.5, and 1.0 in CTAB+ Brij-58 mixture). Pure CTAB stabilized systems produced larger single-phase domains than pure Brij-58 stabilized systems. Increasing temperature increased the single-phase domain in the Brij-58 stabilized systems, whereas the domain decreased in the CTAB stabilized systems. For mixed surfactant systems (with X Brij= 0.5) negligible influence of temperature in the studied range of 293 to 323 K on the phase behavior was observed. Interfacial compositions of the mixed microemulsion systems at different temperature and different …