The paper delivered describes a new approach into kinematics and dynamics of the robots with a tree-like kinematic structure based on the elements of graph theory. Block-matrix equation for robot's movement within generalized coordinates is valid for different tree-like kinematic structures with no change in tracing. It permits to develop generalized software for the whole class of tree-like kinematic structure. Some of the modelling details in hydraulic actuator of bipedal robot are submitted. Experimental research data of robot's walking based on mathematical modelling are compared to those of a pilot model. © 2015 The Authors. Published by Elsevier Ltd.