Prof. Szász designed his first oncothermia device in 1990. It used only electric fields for the treatment of patients. In most of the cases, despite the first applications on advanced tumours, patients in terminal-phase; significant regression had been observed. The time afterwards also brought success in the development and testing of electro-hyperthermia equipment. In 2001, more than 100 devices were in operation, primarily in Germany and in Hungary. Nowadays 100.000 treatments are provided in a year by OncoTherm devices.

Professor Szász is the research director of the self-founded OncoTherm Ltd. The business is managed by his son, Dr. Olivér Szász, who is an electro-engineer. Prof. Szász receives intensive support from his family. His wife Dr. Susan Csih-Szász, who is also a physics expert, as well as his daughter Dr. Nóra Szász , an electro- and bio-engineer, also have a share in the high-level work of the company.