Shape memory alloys are a specific group of materials exhibiting special behaviors which are not seen in other materials. One of these behaviors is shape memory effect, which is related to fully recovery of inelastic strain, caused by loading, due to heating. The other outstanding behavior of these alloys is pseudoelastic effect. Pseudoelastic effect is related to fully recovery of inelastic strains, caused by loading, in the course unloading. Shape memory alloys have growing usage in several areas such as robotics, aerospace, biomechanics and military industries. The aim of this thesis is to numerically and experimentally investigate the electro-thermo-mechanical behavior of thin wires in the mode of shape memory effect. In order to numerically simulate the electro-thermo-mechanical behavior of these alloys, Mohagheghain’s electro-thermo-mechanical model is used. This model, by appending the term of thermal heating, is an extended version of Kadkhodaie’s 1D thermo-mechanical modelm which is derived in a continuum framework. Thermal heating, which has not being noticed in other constitutive models, is important because the most logical and the fastest way to heat these alloys, specially in actuator applications where time response is of importance, is applying electrical current. Simulations contain strain recovery under constant and variable stresses during electrical heating. A constant stress is applied with a dead load, and variable stresses are applied using some bias springs. In order to perform experimental tests, as there was no suitable setup, required equipment for performing electro-thermo-mechanical tests under constant and variable stresses are made. Because of the appearance of the intermediate phase during cooling in the tests, it was decided to investigate the electro-thermo-mechanical behavior of these alloys in the presence of the intermediate phase. In this manner, the performed tests led to proposing a rhombohedral phase diagram. Intermediate or rhombohedral phase plays a significant role in design of shape memory actuators, and neglecting the effects of this phase may lead to considerable errors. In the next part of the thesis, in order to eliminate this intermediate phase, samples are submerged in liquid Nitrogen to completely transform intermediate phase to martensite and therefore the initial phase in the tests would be pure martensite. In a specific pre-stress, time response of a sample in both steps of heating and cooling in three situations of pure martensite, a combination of martensite and rhombohedral phases, and pure rhombohedra are compared; Also tensile tests are carried out on the samples in both pure martensite case and mixture of martensite and rhombohedral case. Electro-thermo-mechanical tests for pure martensite case contain two steps: one at a constant stress and another at variable stresses. In both constant-stress and variable-stress cases, tests are performed with various amount of pre-stresses. Since the intermediate phase just appears during cooling stage and also the model used here can only predict martensite to austenite and austenite to martensite transformations, just the forward (heating) stage is compared to the obtained numerical simulations. Finally the ability of the proposed model in predicting the electro-thermo-mechanical behavior of shape memory alloys in the absence of intermediate phase is investigated. Keywords: Electro-thermo-mechanical model, Shape memory alloy, Pre-stress, Phase diagram, Martensite, Austenite, Rhombohedral, Intermediate phase