A robotic packing system allows to compute optimal solutions to the bin-packing problem and to execute those solutions (loading / unloading task) with robotic platforms. One of the modules associated with this system is the kinematic model of the manipulator. This article documents the computing and validation of forward and inverse kinematic model of the HP20D manipulator, adapted for packing applications. The applied methodology consists of four stages: (1) obtaining the direct and inverse kinematic model of the robot, (2) selection of the reference models and test points, (3) development of applications for registration of joint variables of the test points and (4) validation of the model by comparison with output data from two reference models: (a) model encoded in the DX100 controller, (b) model integrated in the MotoSim simulation tool. The results obtained allow concluding that our model has a good performance for the packing application.