The thesis deals with problems of control and diagnostics of electron beam technological devices which use electron beam for localised intensive heating of a material. A brief description of the electron beam welder MEBW-60/2 is included; the author has participated on its development and implementation. Main topics are the analysis of deflection system properties and the measurement of current distribution of the beam (so-called beam profiles). Geometrical aberrations, hysteresis, stability and dynamics of a single-stage magnetic x-y deflection system are described. Suitable measurement procedures and correction methods are introduced. Methods of transverse and longitudinal beam profile acquisition is presented using successive sampling of the local current density of the beam by a modified Faraday cup. The data processing and evaluation of characteristic beam parameters are shown. The presented methods were verified by fourteen experiments using the electron beam welder. The methods have proven to be useful in practical evaluation of the device properties.