Since December 1986, we have been engaged in high Tc oxide superconductor research with emphasis on the synthesis and processing of thin and thick films of cuprate superconductor as well as on the accumulation of some basic data related with the film preparation. This paper reports some of our recent results of film deposition and photochemical processing of the films. 50Hz ac sputtering has been primarily used for preparing a variety of high Tc films by use of its simple and easily modifiable system. A plasma controlled sputtering is applied to the currently interested layer-by-layer deposition of oxide films as a possible approach to new higher Tc materials. Annealing of films under a laser or a UV light irradiation worked effectively to control the oxygen stoichiometry and induced reversible changes in Tc and crystal parameters of the films.