Abstract We report the effect of average A-site cation radius on the structural, magnetic and electrical properties of electron doped manganite La 0.7Ce 0.3MnO 3 thin films. A site cation radius 〈 r A〉 is varied systematically by partially replacing La +3 ions by smaller Y +3 ions in the parent compound. The carrier doping, i.e. the fraction of tetravalent Ce atoms at the A-site was kept at 30%. A series of La 0.7− x Y x Ce 0.3MnO 3 ( x=0, 0.05, 0.1, 0.15 and 0.25) thin films were prepared under identical conditions by using pulsed laser deposition technique. Metal–insulator transition temperature ( T p) and the ferromagnetic Curie temperature ( T c) are found to be decreasing significantly with increasing yttrium concentration, i.e. decreasing 〈 r A〉. The resistivity ( ρ) at T p increases by one order of magnitude when the yttrium concentration is increased from x=0 to 0.25, while magnetization decreases with decreasing 〈 r A〉. Magnetoresistance as measured under field of 1 T is significant near T c. Structural analysis reveals the films are having single phase and c-axis lattice parameter decreasing linearly as 〈 r A〉 decreases. There is no marked difference in surface morphology of samples with different yttrium concentration. From EDX the Y:Ce:Mn ratio were consistent within 5% of the nominal composition.