This review summarized my works concerning with the JOCS Award 1990 under the title mentioned above. It was mainly consisted of following items; 1) properties of substituted long-chain alkylphosphonic acids, 2) preparation of alkylphosphonic acids by radical reactions, 3) dealkylation of the dialkyl ester with a mixed reagent of Me3SiCl/NaI or LiBr, 4) biological activities of aminodiphosphonic acids, 5) phosphorylation of alcohol by oxidation of P-H compounds with oxygen by coupling with the oxidation-reduction cycle of copper chloride, and 6) photo-chemistry of organophosphorus compounds : photochemical C-P bond cleavage of arylmethyl-phosphonic acids and formation of monomeric metaphosphate anion, novel photo-generation of phosphono (aryl) carbene from triarylmethylphosphonic acids, photo-coupling of two aryl groups of diaryl alkylphosphonates, and others. References cited in this review are 121.