The purpose of this review is to identify the areas in thermal plasma processing for coating fields where scientific and/or engineering advances would have been highly expected in the near future. In particular, we characterize three types of injection plasma processing(IPP) for coating, that is, thermal plasma CVD, plasma flash evaporation, and plasma spraying, and discuss the problems relating to each IPP. In order to demonstrate the prominent features of IPP, special attention will be given to radio-frequency(rf) and hybrid plasma processing, which will be discussed in conjunction with our recent research concerning the functional materials coatings. ''Super-high rate and large area deposition of SiC and diamond by hybrid plasma CVD'', ''Large area deposition of high-quality YBCO films by rf plasma flash evaporation'' and ''Integrated fabrication of solid oxide fuel cell by hybrid plasma spraying'' will be mentioned as three distinctive candidates, which should suggest the way of thinking for the future development of IPP in the field of functional materials coatings.