| Cosmic Hydrogen Energy Limited | | Live |
| Super Hydrogen Energy Company Limited | Private company limited by shares | Live |
| CHINA HYDROGEN ENERGY UNITED LIMITED | Private company limited by shares | Live |
| Hydrogen Happy Limited | Private company limited by shares | Live |
| Pinnacle Fitness (Hydrogen) Company Limited | | Live |
| Green Hydrogen Technology Limited | | Live |
| Hydrogenation IP Company Limited | Private company limited by shares | Live |
| China Hydrogenergy Technology Co., Limited | Private company limited by shares | Live |
| HYDROGLOBE LIMITED | Private company limited by shares | Dissolved |
| FUGRO HYDROGRAPHIC SURVEYS LIMITED | Private company limited by shares | Live |
| Hydrogreen Production Limited | Private company limited by shares | Live |
| Hydrogreens Technology Limited | Private company limited by shares | Live |
| Hydrogro Company Limited | Private company limited by shares | Live |
| HYDROHEALTH LIMITED | Private company limited by shares | Live |
| HYDROHEATING LIMITED | Private company limited by shares | Live |
| HYDROHOUSE COLON HYDROTHERAPY LIMITED | Private company limited by shares | Live |
| HYDROLATINA CO., LIMITED | Private company limited by shares | Live |
| HYDRO-LOC TECHNOLOGY LIMITED | Private company limited by shares | Live |
| HYDROMATE LIMITED | Private company limited by shares | Live |
| HYDROMATE (H.K.) LIMITED | Private company limited by shares | Dissolved |
| Hydromax Limited | Private company limited by shares | Dissolved |
| HYDRO-MAX FITNESS & BEAUTY LIMITED | Private company limited by shares | Dissolved |
| HYDROMET SOUTH EAST ASIA LIMITED | Private company limited by shares | Dissolved |
| China HydroMg Biotechnology Co., Limited | | Live |
| HYDRO-ORIENT LIMITED | Private company limited by shares | Live |
| HYDROPON LIMITED | Private company limited by shares | Dissolved |
| A&T HYDROPONIC LIMITED | Private company limited by shares | Live |
| Hydroponics Limited | Private company limited by shares | Live |
| NL HYDROPONICS LIMITED | Private company limited by shares | Live |
| ECO HYDROPONICS LIMITED | Private company limited by shares | Live |
| GUANGDONG GREEN CYCLE HYDROPONICS CO., LIMITED | Private company limited by shares | Live |
| ZIMBRICK HYDROPONICS LIMITED | Private company limited by shares | Live |
| HYDROPOWER LIMITED | Private company limited by shares | Live |
| NAM THA HYDROPOWER COMPANY LIMITED | Private company limited by shares | Dissolved |
| Wah Fu Hydropower Limited | Private company limited by shares | Live |
| XINHUA HYDROPOWER INVESTMENT CO., LIMITED | Private company limited by shares | Dissolved |
| Xinhua Hydropower Investment Company Limited | Private company limited by shares | Live |
| NICE HYDROPOWER LIMITED | Private company limited by shares | Dissolved |
| Team-Tech Hydropower Limited | Private company limited by shares | Live |
| Hydropure (HK) Limited | Private company limited by shares | Dissolved |
| HYDROPURE (INTERNATIONAL) LIMITED | Private company limited by shares | Live |
| Hydros Argos Investment Limited | Private company limited by shares | Live |
| HYDROSA TRADING LIMITED | Private company limited by shares | Live |
| Hydroscience Resources Limited | Private company limited by shares | Live |
| HydroSeal Limited | Private company limited by shares | Dissolved |
| HYDROSEAL CANADA LIMITED | Private company limited by shares | Live |
| HYDROSEAL CANADA PIPING SYSTEMS CO., LIMITED | Private company limited by shares | Live |
| HYDROSEAL CANADA PRODUCT MANAGEMENT LIMITED | Private company limited by shares | Dissolved |
| HYDROSEAL CORPORATION LIMITED | Private company limited by shares | Live |
| HYDROSOFT LIMITED | Private company limited by shares | Live |
| Hydrosonic Limited | Private company limited by shares | Live |
| HYDROSPA LIMITED | Private company limited by shares | Live |
| HydroSpotless Company Limited | Private company limited by shares | Live |
| HYDROSTAR HK LIMITED | Private company limited by shares | Live |
| USA HYDRO-STOP (CHINA) LIMITED | Private company limited by shares | Live |
| HYDROSUN CANADA LIMITED | Private company limited by shares | Live |
| HYDROTEC CO., LIMITED | Private company limited by shares | Dissolved |
| HYDROTEC HYDRAULIC TECHNOLOGY LIMITED | Private company limited by shares | Dissolved |
| HYDROTECH R & D LIMITED | Private company limited by shares | Dissolved |
| HYDRO-TECH LIMITED | Private company limited by shares | Live |
| HYDROTEK COMPANY LIMITED | Private company limited by shares | Dissolved |
| JUST WALK ANIMAL HYDROTHERAPY COMPANY LIMITED | Private company limited by shares | Live |
| Asia Pacific Hydrotherapy Rehabilitation Research Center Limited | Private company limited by shares | Live |
| HYDROHEALTH COLON HYDROTHERAPY LIMITED | Private company limited by shares | Live |
| WATER-CUBE INT'L HYDROTHERAPY PLAN MANAGE GROUP (HK) LIMITED | Private company limited by shares | Dissolved |
| Hong Kong Hydro-therapy Tutor Association Limited | Company limited by guarantee | Live |
| INT'L SWIMMING POOL HYDROTHERAPY GROUP LIMITED | Private company limited by shares | Dissolved |
| OASIS HYDROTHERAPY SYSTEMS LIMITED | Private company limited by shares | Live |
| Germany Slow Old Hydrotherapy Electrical Co., Limited | | Live |
| HydroTide Company Limited | Private company limited by shares | Live |
| Hydroverse Company Limited | | Live |
| HYDROVICTOR HONG KONG LIMITED | Private company limited by shares | Dissolved |
| HYDROWEAR ASIA LIMITED | Private company limited by shares | Live |
| Hydrowise Limited | Private company limited by shares | Live |
| Hydroworks Limited | Private company limited by shares | Live |
| HydroWorld LIMITED | Private company limited by shares | Live |
| HydroX Group Limited | | Live |
| HYDROX (HK) LIMITED | Private company limited by shares | Dissolved |
| HYDROX TECHNOLOGY LIMITED | Private company limited by shares | Dissolved |
| HYDROXY LIMITED | Private company limited by shares | Live |
| HYDRUS HK LIMITED | | Live |
| Hydsoft Co., Limited | Private company limited by shares | Live |
| Hydsoft International Limited | | Live |
| HYDTRADE CO., LIMITED | Private company limited by shares | Live |
| HYDY Operations (HK) Limited | | Live |