Prompt Techno Service is a Joint-Venture established since 1992 between Teo Hong Silom Co., Ltd. and Elyo S-East Asia Pte., Ltd., a subsidiary of ELYO (visit them at, which has an annual turnover over 2 billion US as the energy arm of French group Suez-Lyonnaise des Eaux.

Prompt Techno Service is present in Bangkok area, eastern seaboard and south of Thailand with a force of more than 360 staff engineers and technicians.