The effect of low amounts of dysprosium, samarium and manganese (0.1-0.5 at.%) on the properties of the chalcogenide glassy semiconductors As₂S₃ and As₂Se₃ is investigated. The metals have significant influence on the structural, optical, electrical and photoelectric characteristics. The fundamental absorption edge shifts towards longer wavelengths with doping. The largest shift was observed for As₂S₃ glasses doped with Dy and Mn. The conductivity is significantly increased by addition of Mn and Dy. All the dopants hamper the photoconductivity with the exception of 0.5 at. % Dy in As₂Se₃ which generates a broad secondary band in the photoconductivity spectrum near 1.05 eV, ascribed to small amounts of crystalline phase. Close correlation was revealed between the medium range order in the network, the metal eleclronegativity and the activation energy of conductivity.