Recently, by the advent of modern technologies; such as electrospinning and other technologies, the processes of producing nanofibers have improved significantly. Due to having high aspect ratio and surface porosity the nanofibers reveal unique characteristics. The porosity of electrospun nanofiber is attributable to the application of volatile solvent and consequently a rapid phase separation in the production process. There are various methods in order to produce nanofibers all of which produce nanofibers as a nonwoven layer. The application of various nanoparticles in mixture with the polymer solution or as a coating on the nanofibers, are subjects of some recent researches on nanofibers. In the present research, the dyeing behavior of the nanofibres was investigated and the hydrolyzes of the PET nanofibers with an alkaline solution was performed to induce surface porosity on the nanofibers and to improve their dyeing behavior. To do so, polyester chips, in different concentrations, were dissolved in TFAA and DCM and the resultant solutions mixed with different w/w percentage of TiO 2 nanoparticles and the mixture were electrospun. The average diameter of the nanofibers was between 250-350 nm. The nanofibers were then hydrolyzed with the alkaline solution, and the hydrolyzed and non-hydrolyzed samples were dyed with a disperse dye. Also the hydrolyzed and non-hydrolyzed nanofibers were treated with a fluorocarbon component to make a superhydrophobic surface. The samples were examined for the nanofiber diameter and morphology using SEM and XRD techniques. The dye exhaustion, contact angle and sliding angle of the samples were also examined. The results showed that the nanofibers have amorphous structure and the higher concentration of the nanoparticles, the higher is the amorphosity of the nanofibers. Also, it was shown that the alkaline treatment leads to the higher surface porosity of the nanofibers and the surface porosity is higher for the samples with higher nanoparticles’ concentrations. The dyeing experiments indicated that the dye exhaustion and the rate of dyeing were increased by the addition of the nanoparticles and hydrolyzing the samples. Finally, a superhydrophobic nanofibers with 156? contact angle was produced by the mutual effect of the addition of the TiO 2 nanoparticles and the alkaline treatment. Keywords: electrospinning, polyester nanofibers, TiO 2 nanoparticles, alkali hydrolysis, dyeing, disperse dyestuff, superhydrophobic surface