The Y2−xSrxBaNiO5 (x=0, 0.1, 0.2 and 0.3) acceptor substituted system has been synthesized by solid state reaction. Structural and microstructural properties have been characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Lattice volume is shown to decrease linearly with increasing Sr content until composition x=0.2, highlighting the limit of the solid solution. The electrical response in the temperature range (700–100°C) was assessed by A.C. impedance spectroscopy in wet and dry O2 and N2 atmospheres. Conductivity measurements as a function of oxygen partial pressure (pO2) were also performed. The data reveal that the conductivity Y2BaNiO5 can be increased by one and half orders magnitude by Sr-doping and is independent of both water vapour and oxygen partial pressures (pH2O and pO2). The low activation energy for electrical conduction (0.216–0.240eV) suggests a thermally activated electron hopping mechanism, while the observed pO2 and pH2O independence of conductivity suggests that charge compensation for Sr is predominantly by formation of Ni3+ rather than formation of oxygen vacancies.