The mechanical and functional properties of thermo-regulating hexadecane-polyurethane (HD-PU) nanofiber/net membrane (NFNM) with potential application in protective clothing were modeled and optimized. The optimum conditions for fabrication of the HD-PU NFNM were obtained using response surface methodology (RSM). Central composite design (CCD) matrix was employed to develop predictive regression models along with optimize and investigate the effects of important parameters such as PU and surfactant concentrations, and co-electrospinning time, on the responses. Mechanical and functional properties of protective membranes including strength, elongation, water vapor transmission rate (WVTR), hydrostatic pressure, air permeability, and enthalpy of fusion were optimized as responses. As a result, higher NFNM strength was observed by increasing PU and surfactant concentrations. Thermal regulating efficiency (TRE) or HD loading amount for optimized NFNM was calculated using the results of RSM and experimental data, and it was obtained as 28% and 24%, respectively. Therefore, remarkable agreement with errors lower than 12% between predicted and experimental values was achieved. According to our findings, NFNM characteristics can be improved under controlled conditions and RSM is an efficient method to predict and optimize these conditions. POLYM. ENG. SCI., 58:1756-1765, 2018. (c) 2018 Society of Plastics Engineers