For the history of the Taiyo Nippon Sanso Group prior to 2004,
see "History of Nippon Sanso Holdings" on the website of Nippon Sanso Holdings Corporation,
which transitioned to a holding company structure in October 2020.
- Merged with Taiyo Toyo Sanso Co., Ltd. to create Taiyo Nippon Sanso Corporation. Moved its head office to Koyama, Shinagawa-ku, Tokyo.
- Merged Dia Reiko Kogyo Co., Ltd., (a subsidiary company in the cryogenic equipment business), and Nissan Kogyo Co., Ltd. to create Cryo One Inc.
- Merged Ozawa Sanso K.K., (a group company of Taiyo Nippon Sanso in medical-related business), Yamato Sanki K.K., and Suzusho Medical Co., Ltd., (a subsidiary of Suzuki Shokan Co., Ltd)., to create Nippon Megacare Corporation.
- Acquired the shares of Nippoku Sanso K.K. (currently Taiyo Nippon Sanso Hokkaido Corporation), an industrial gas manufacturer in Hokkaido.
- Acquired all the shares of Hitachi Sanso K.K. to make it a wholly owned subsidiary named Taiyo Nippon Sanso Higashikanto Corporation.
- Merged Nippon Tansan Co., Ltd., Ekika Tansan Co., Ltd., their holding company Nippon-Ekitan Holdings Corporation, and the carbon dioxide business of Taiyo Nippon Sanso, to create Nippon Ekitan Corporation.
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Established Taiyo Nippon Sanso (China) Investment Co., Ltd., an investment company, and Dalian Changxing Island Taiyo Nippon Sanso Gas Co., Ltd., an industrial gas manufacturer, in Dalian’s Changxing Island Seaport Industrial Area in China.
- Reorganized the roles and functions of Saan Engineering Corporation and NS Engineering Corporation into Taiyo Nippon Sanso Engineering.
- Acquired a 51% share of K-Air India Gases Pte. Ltd., a manufacturer and distributor of industrial gases in India, and renamed it as Matheson K-Air Gases India Pte. Ltd. (currently Taiyo Nippon Sanso India Pvt. Ltd.).
- Made a takeover bid for Leeden Limited to make it a wholly owned subsidiary via its wholly owned subsidiary Taiyo Nippon Sanso Singapore Pte.
- Merged Saan-Tech Corporation, Futaba Bussan Corporation, and Toei Kagaku Corporation to create Taiyo Nippon Sanso Gas and Welding Corporation.
- Acquired all the shares of Pacific Medico Co., Ltd., a manufacturer and distributor of medical equipment.
- Acquired all the shares of Continental Carbonic Products, Inc., a manufacturer and distributor of liquid carbon dioxide gas and dry ice in the U.S.
- Established PT. Samator Taiyo Nippon Sanso Indonesia on the island of Java, Indonesia, as a joint venture with Samator, an industrial gas manufacturer in Indonesia, and National Oxygen, a subsidiary in Singapore.
- Established Taiyo Nippon Sanso Holdings Singapore Pte. Ltd., the regional headquarters in Southeast Asia.
- Merged three of the Singapore-based consolidated subsidiaries to create Leeden National Oxygen Ltd.
- Became a consolidated subsidiary of Mitsubishi Chemical Holdings Corporation (currently Mitsubishi Chemical Group Corporation) as a result of the conclusion of the tender offer for the company's shares.
- Merged five subsidiaries in the LP gas industry to create Taiyo Nippon Sanso Energy Corporation.
- Acquired Air Products Industry Co., Ltd., a company accounted for using the equity method in Thailand, and made it a consolidated subsidiary.
- Acquired Renegade Gas Pty Ltd. (currently Supagas Pty Ltd), a distributor of industrial gases in Australia.
- Established Yahata Sanso Center Corporation (currently Kyushu Sanso Center Corporation) jointly with Nippon Steel & Sumitomo Metal Corporation (currently Nippon Steel Corporation).
- Acquired part of the U.S.-based industrial gas business and related assets of Air Liquide via Matheson Tri-Gas, Inc.
- Established Taiyo Nippon Sanso Myanmar Co., Ltd., a manufacturer and distributor of industrial gases in Myanmar, via Taiyo Nippon Sanso Holdings Singapore Pte. Ltd.
- Acquired Taiyo Gases Co., Ltd., a distributor of industrial gases in Thailand.
- Acquired Supagas Holdings Pty Ltd (currently Supagas Pty Ltd), a manufacturer of industrial and LP gases in Australia, via TNSC (Australia) Pty Ltd (currently NSC (Australia) Pty Ltd)
- Established JFE Sanso Center Kurashiki Plant as a result of the transfer of operations and maintenance of the air separation plants in West Japan Works (Kurashiki Area) from JFE Steel Corporation.
- Established the Technical Academy as a hub for technological education.
- Acquired all the shares of IMI Co., Ltd., a distributor of medical equipment.
- Acquired the shares of the corporations running part of the European business of Praxair via Nippon Gases Euro-Holdings S.L.U., etc.
- Acquired part of the HyCO business and related assets of Linde Gas North America LLC (currently Linde Gas & Equipment Inc.) via Matheson Tri-Gas, Inc.
- Taiyo Nippon Sanso Corporation Split Preparation Corporation was established in preparation for the transition to a holding company structure.
- Taiyo Nippon Sanso Corporation converted to a holding company structure and its trade name changed to Nippon Sanso Holdings Corporation.
- Manufacturing and sales of industrial gas and related equipment in Japan was taken over by Taiyo Nippon Sanso Corporation Split Preparation Corporation and its trade name changed to Taiyo Nippon Sanso Corporation.
- Pacific Medico Co., Ltd. was merged with IMI Co., Ltd. , which remains as the surviving company.
- Invested in Minnano Taiatsuba Corporation, a new company that inspects high-pressure gas containers.
- Hachioji Gas Center installed a self-consumption solar power generation system to power the gas filling equipment in a sustainable way.
- Toho Nippon Sanso Gas Center Co. Ltd., a filling station jointly owned by Taiyo Nippon Sanso Corporation and Toho Acetylene Co., Ltd., started operation.
- Toyo Koatsu Gas Co., Ltd., a filling station jointly operated by Taiyo Nippon Sanso and Koatsu Gas Kogyo Co. Ltd., started operations at its new filling station.
- Kitakyushu Gas Center Co., Ltd., a newly established jointly operated filling station with Koatsu Gas Kogyo Co. Ltd., started operations.
- Established Kimitsu Sanso Center Corporation jointly with Nippon Steel Corporation.
- Established a new specialty gases logistics base in Kikuyo-cho, Kikuchi-gun, Kumamoto Prefecture.