In-situ growth of 2-in. diameter superconducting YBa 2 Cu 3 O 7 - x (YBCO) thin films using an excimer KrF pulsed laser has been studied. Films with critical transition temperature (T c , 0 ) of 89 ± 1 K and critical current density (J c , 7 7 K ) in excess of 1 10 6 A cm - 2 have been prepared routinely. Uniformity in film thickness of below ± 15% and film composition of ± 5% have been measured. The effects of gas nozzle geometry and target evolution during ablation on the superconducting properties and surface morphology of YBCO thin films have also been investigated.