Ozone generating machine (OGM) for generating ozone in a ship, comprising: an ozone generator with at least two electrodes separated by an ozonizing gap and at least a gas inlet for receiving a feed gas containing dioxygen, and a gas outlet for exhausting gas comprising ozone to an ozone circuit of the ship, a main liquid cooling circuit (CWP, CWT), with at least a cooling portion in the ozone generator, to be connected with a cooling circuit of a ship, a liquid-liquid heat exchanger (LLHEX) connected with the main liquid cooling circuit (CWP, CWT), and an electrical closed cabinet (ECB) comprising an electric current converter (ECV), characterized in that the ozone generating machine (OGM) further comprises a closed loop cooling liquid circuit (CLC) comprising a converter liquid cooling portion (CECV) arranged to cool the electric current converter (ECV) and connected with the liquid-liquid heat exchanger (LLHEX).