It is well known that by means of mutual diffusion one can obtain strong compounds between metals and alloys. In cases when the combination takes place through a liquid, for instance the eutectic layer; being formed in mutual diffusion of contacting metals, then this phenomenon is called diffusion soldering. Such soldering, when the use of brazing is excluded, has great significance in the fusion of thin walled machine components. The mechanism of diffusion soldering is obtained by the mutual diffusion of contacting metals (or alloys). This article deals with the results of investigations on the structure of diffusion zones, which resulted during the soldering of titanium alloys.