Phase change materials (PCMs) are substances that are capable of storing or releasing a large amount of energy as they melt and solidify at a specified temperature range. Due to the increasing consumption of limited fossil fuel and worsened the environment, the use of PCMs for heat energy storage is becoming increasingly important both strategically and economically. The microencapsulation of PCMs provides some benefits effects on the thermal storage, transition, and application properties. Nowadays, PCMs have drawn increasing interest to provide enhanced thermal functionalities in a wide variety of applications such as thermo regulating textiles, solar energy absorber, building, etc. Up to now, there have been many methods to encapsulate PCMs, but it is still significant and desired to develop facile and controllable methods to encapsulate PCMs with biopolymer shell. In this thesis, the developmental electrospray method called melt-coaxial electrospray was used for encapsulation of PCMs. The n-nonadecane as core material and sodium alginate and chitosan as shell polymer was used. Taguchi method was used to optimum the encapsulation conditions, reduce the experimental time, and statistical analysis of the results. The effect of experimental parameters, parameters meaningful, and the role of each parameter were studied using Minitab 15. The effective parameters were considered including alginate concentration, the feed rate of the polymer solution, the feed ratio of the shell to the core, needle gauge, needle length, electrospray distance, and magnetic stirring speed. The results show that alginate concentration and needle gauge have the highest effect, and needle length and magnetic stirrer speed have the lower effect on properties of capsules. Four different structures of the coaxial nozzle were produced to feed the core and shell material separately. According to the figures obtained from optical microscopy, the optimum coaxial nozzle was selected as the inner needle exit is approximately 0.5 mm above the outer needle exit. The production of alginate/nonadecane capsules was confirmed by optical microscopy images; Fourier transformed infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). DSC analysis indicated that microcapsules consisted of 82 wt% n-nonadecane. Results from scanning electron microscopy (SEM) showed that the uniform circular microcapsules can be obtained by regulating of coaxial electrospray parameters. The results also showed that the capsules with a diameter lower than 200 nm can be achieved. The cotton fabric was used to prepare the thermo-regulating fabric. Results from thermal analyses showed that the finished fabric with a binder containing PCM capsules have the significant effect on t hermo regulating of fabric in the temperatures range of melt point of PCM. The results of this study indicated that the temperature of treated fabric with PCM capsule is lower than untreated fabric in a warm environment. Moreover, the results showed that the PCM capsules kept the fabric temperature in the range of 30-35 °C for 9-15 min with increasing the temperature of environments. Keywords: Coaxial Electrospray; Nano and Microcapsule; Phase Change Materials; Sodium Alginate; Thermo regulating Fabric.