From impedance spectroscopy combined with thermal gravimetric analysis (TGA), the conductivity properties and the defect chemistry of a nominally 5 mol% Y-doped SrZrO3 single crystal are derived. in the temperature range from 60 to 740 degrees C, in which the charge carrier concentrations are frozen-in, proton, hole and oxygen vacancy conductivity with migration energies of 0.47 eV, 0.84 eV and 1.0 eV dominate in different atmospheres. The proton concentration is determined consistently from the water incorporation measured by TGA and conductivity data yielding a saturation concentration of 0.08 mol%.