The paper describes the validation of a dynamic model of a planar robotic arm using gravity tests. The drive of the arm (fluid muscles from the manufacturer Festo) was not activated during gravity tests (for the test was used only gravitation of solid). The measured data were obtained under the conditions that the joint angle was from 20° to 40°, the measurements were performed 10 times for each angle and at the same time independent for both links. The dynamics simulation was performed in the MATLAB® and Simulink environment, using the created simulation scheme, which presented the dynamics of the manipulator's arm with the inclusion of the friction component. The simulation results were compared with the measured data using two criteria (MAE - Mean Absolute Error and Fgof - Goodness of Fit).