The corm and innovative B-doped diamond electrodes, based on Nb and SiC-graphite substrates, resp., were used sep. as anodes in lab. equipment for studying the degrdn. of dissolved org. C (DOC) contained in solns. of KH phthalate. The initial DOC concn. (DOC0) was 10-1000 mg/L. The degrdn. kinetics was of pseudo-first order. The DOC/DOC0 ratio was independent form DOC0. In addn., the electrochem. oxidn. of KH phthalate soln. at DOC0 100 mg/L and current 0.5 A was performed on B-doped diamond electrodes (grain size 0.12-2.16 micrometers). The replacement of Nb substrate with SiC-graphite one did not result in any decrease in the electrode efficiency.