Cisplatin has been an important platinum-containing anticancer drug for years. Toxic effects of cisplatin and the resistance of tumor cells against treatment lead to new studies about finding new Pt- containing anticancer drugs. In this study, the electronic properties and reactivity indices of cisplatin and its clinically accepted derivatives carboplatin, oxaliplatin, nedaplatin, lobaplatin, and heptaplatin were calculated by density functional theory (DFT). These properties of drugs have been calculated in both vacuum and aqueous medium. The reactivity of the molecules is explained with the global reactivity indices. Local reactivity indices were used to examine the reaction of the hydrolyzed nedaplatin complex with the amino acid cysteine. In anticancer drugs containing Pt, the platinum atom is an important reaction site for anticancer mechanisms.