In this paper, we describe the bases of the experimental technique to produce bicrystal specimens by diffusion bonding, especially in the case of two crystals of different kind. Details are given on the special cares to be taken during the procedures for preparation of the single crystal elements, for their relative positionning, and for the diffusion bonding annealing under compressive load. The theoretical models which may be useful to control the kinetics of bonding are also presented, and the influence of the main operation parameters - i.e. temperature, bonding pressure, annealing duration, geometry and finish of the surfaces to be bonded - is discussed. The interdiffusion phenomenon through the phase boundary during annealing is described and analysed. Various techniques for controlling and characterizing the bonded bicrystals are exposed. Examples are taken in literature and among heterophase bicrystal systems previously prepared and studied, such as Al/Al₂CU, Ag/Cu, Ni/Ni₃Al and Ni/Al₂O₃.