Abstract: Novel cephalosporin derivatives, for example N-acetoacetylcephalosporin C, N-decanoylcephalosporin C, N-dodecanoylcephalosporin C and N-hendecenoylcephalosporin C, are useful as readily-recoverable intermediates in the isolation of cephalosporin C value from fermentation broths and in the preparation of 7-aminocephalosporanic acid. They are prepared by treating an aqueous solution containing cephalosporin C, such as a fermentation broth, with diketene or an acid chloride such as decanoyl chloride, dodecanoyl chloride or hendecenoyl chloride, followed by solvent extraction. They are converted into 7-aminocephalosporanic acid by successively forming the silyl di-ester, halogenating to the imino-halide, converting the imino-ether and hydrolysing to 7-ACA.