Taurolidine, a derivative of the amino acid taurine, is an antibiotic clinically used after peritonitis surgery. It has been widely used, particularly in Europe and, remarkably, has no known side effects. Recent studies also show anti-tumor activity against a variety of cancers including ovarian, leukemia, melanoma, colon adenocarcinoma, prostate and brain. Since a clear response to using taurolidine is seen in tumors that have few therapeutic options, there is much interest in knowing taurolidine's mechanism of action. Interestingly, the antitumor activity is observed at much lower dose than when used as an antibiotic. Taurolidine shows reduction of metastases after tumor surgery of mice previously inoculated with melanoma tumor cells. Thus far, its biological mechanism is associated with apoptosis by mitochondrial cytochrome c dependent pathway for melanoma. The chemical evolution of taurilodine in water solution is associated with successive hydrolysis steps until the active product is formed. We present here the X-ray molecular structure determination of taurolidine along with a Density Functional Theory description of its hydrolysis decomposition.