The development of new materials with specific properties leads to higher demands regarding the joining procedures. Diffusion welding is a solid-state joining procedure capable of joining a wide range of material combinations. The potential of diffusion bonding lies in specialized joining applications where retention of the solid solution is important. In this paper, a discussion of the fundamentals factors governing the diffusion welding process have been outlined. The process is dependent on a number of parameters, in particular, time, applied pressure, bonding temperature, atmosphere and surface conditions.