<p>Process for producing Lactol-type Cephalosporins A 3-hydroxymethylcephalosporin which is not protected at the carboxyl group can be directly oxidized with a hexavalent chromium compound to give in good yield a lactol type cephalosporin represented by the general formula: wherein R1 is hydrogen or an alkoxy group and R2 is an acylamino, or imido group. The resulting compounds are very useful and important as intermediates for preparing, e.g. 3-alkoxyiminomethyl cephalosporins.</p>
