Thin films of YBCO have been grown by a home-built-MOCVD vertical reactor. The growth temperature were varied between 600 and 750 degreesC and the growth rates were 0.4-0.5 mum/h. At the substrate temperature between 630 and 675 C, the films consist of a mixture of a-axis and c-axis oriented grains, while at temperature of 700 degreesC or higher, the a-axis oriented grain changed to random orientation. The stoichiometric composition of Y:Ba:Cu for films grown at 680degreesC or higher is almost 1:2:3, as confirmed by electron dispersive X-rays (EDAX) spectra. Films deposited at 680 and 700degreesC show superconducting critical temperature around 87 and 87.4 K, respectively. Films properties are comparable with film grown using horizontal MOCVD reactor reported by previous reports. (C) 2002 Elsevier Science B.V. All rights reserved.