Crystalline 2-(amninothiazol-4-yl)-2-(tert.butoxycarbonylmethoxyimino)acetic acid-S-mercapto-benzo-thiazolylester in form of an N,N-dimethylacetamide solvate; a crystalline salt of a 7-[2-(aminothiazol-4-yl)-2-(carboxymethoxyimino)acetamido]-3-vinyl-3-cephem-4-carboxylic acid with an amine of formula N(R1)(R2)(R3), wherein R1, R2, and R3 have various meanings, a crystalline sulphuric acid addition salt of a 7-[2-(2-aminothiazol-4-yl)-2-carboxymethoxyimino)acetamido]-3-vinyl-3-cephem-4-carboxylic acid; and the use of these salts in the production of cefixime, e.g. in form of a trihydrate.