EN
Effects of slight nonstoichiometry in Gd_{1+x}Ba_{2-x}Cu_{3}O_{7-δ} compounds on superconducting and magnetic properties were studied. The series of single-phase samples of Gd_{1+x}Ba_{2-x}Cu_{3}O_{7-δ} with composition deviation x from the stoichiometric value of 0 to 0.1 and to -0.1 were synthesized by the solid-state reaction method from Gd_{2}O_{3}, BaCO_{3} and CuO precursors, sintered at the temperature of ~ 1000°C in flowing oxygen and annealed at 450°C for 24 h.