Abstarct: Hysteresis motors are of self-starting synchronous motors operating baxsed on hysteresis property of the magnetic materials. baxsed on available references, there are still a lot of questions regarding these motors that are either unanswered or their answers are not inclusive and complete. The effects of partial and harmonic load on motors and low power factor and efficiency are among these questions, to name a few. A proper and inclusive model for motor is needed for answering the questions on Hysteresis motors, their performance analysis and achieving their technical specifications. This model should sufficiently describe the motor’s behavior in all situations such as starting and acceleration regime, steady state operation, dynamic and transient performance as a result of variation in load and input voltage. Hence this thesis aims at modeling and investigating dynamic and transient performance of hysteresis motor. In this work, we derive dynamic and transient equations and provide equivalent circuit of Hysteresis motors then represents the algorithm and updating procedures of equivalent circuit parameters. With choosing Disk-Type Hysteresis Motors of reference [7] as the benchmark motor, dynamic and transient equations are implemented in MATLAB/SIMUlixnk with the use of proposed method and the simulated results are compared with the result of reference [7]. This comparison shows the consistency of the results with each other. Finally, we will analyze the desirable effects of lowering input voltage on Power factor, efficiency and stator current of Hysteresis motor in Non-nominal load situations and the undesirable effects of Harmonic loads on motor’s performance.