Rehabilitation robotics is a rapidly growing field in the engineering industry. Due to the high repeatability of motion, high therapy costs, and lack of proper quantitative assessment of patient status and progress, rehabilitation centers could benefit from the introduction of robotics. One such device already commercially available is the bodyweight supported treadmill device Lokomat (Hocoma, Switzerland). In this thesis, the kinematics analysis for a modified Lokomat orthosis has been made and validated. These kinematics calculate the Euler angles of the orthosis hip joint as a function of eight degrees of freedom, two degrees of freedom of actuators driving the thigh, and six degrees of freedom of the orthosis pelvis body. The kinematics were validated by using a low-cost HTC Vive VR tracker system, to capture the actual angle of the orthosis hip joint. The kinematics were tested in three experiments. Firstly, the kinematics were tested by moving the orthosis around by hand, tracing the range of motion of the linear actuators. Afterward, the kinematics were validated with a person wearing the device. The first dataset has the person suspended in the air, simulating walking, whilst the final dataset has the person dragging their feet over the ground, to simulate walking. The results from the first experiment indicate that the kinematics calculation tracks the measured angles with an RMSE of less than 6% of the total range of motion. Later experiments suffered from drift in the Vive trackers, mainly in the flexion angles, worsening performance. Compensating for this drift shows the kinematics to still be similarly accurate to the first experiment.