The crystal structure and properties of YBa2Cu3Ox (YBCO) thin films on LaSrGaO4 (100) substrate have been investigated as a function of deposition rates in the range of 0.1-12.2 nm/s using different repetition rate of pulsed laser. At a given substrate temperature of 700 degrees C, when the Nm was deposited at low deposition rate of 0.1 nm/s, c-axis oriented orthorhombic YBCO thin film growth was observed. However, at high deposition rate of 12.2 nm/s, cubic YBCO thin film growth was observed. This demonstrates that the shortening of interval time between the vapor pulses is important for the cubic YBCO thin film growth. The cubic YBCO thin film growth under high deposition rates was explained by the cation kinetics. (C) 1998 Published by Elsevier Science B.V. All rights reserved.