| Company Name | Tel | Country/Region | Contact |
| OMEC Instruments Co., Ltd. | 86-756-3395965 | China | |
| Orbitic Engineering Technology Co., Ltd. | 86-21-33750488 | China | |
| OMPI Pharmaceutical Packing Technology (China) Co.,td | 18862638309 | China | |
| O HAISHUO BIOTECHNOLOGY CO.,LTD. | 86-574-59120017 | China | |
| Ovodan Foods(China)Ltd. | 86-21-66309112 | China | |
| OS Chemical CO.,LTD | +86 21 62916331 | China | |
| Optum | 86-21-52110772 | China | |
| Oceanic Pharmachem Pvt Ltd | 91-22-4212 8666 | India | |
| Ocean Optics Asia | 86-4-6232690 | United States | |
| One Source Chem, LLC | 267 908 7900 | United States | |
| Onwon Trading Ltd. | 852 2796 6985 | Hong Kong | |
| Oriental Chemicals & Lab Supplies Ltd. | +852 240 88001 | Hong Kong | |
| Onnesion, Inc. | 508 755-7531 | United States | |
| ORGANICA Feinchemie GmbH | +49 3494636389 | Germany | |
| OriBase Pharma | +33 04 67 727 670 | France | |
| Oakwood Products, Inc. | 803 739 8800 | United States | |
| OKEANOS TECH CO LTD | 86 10 62651721 | China | |
| Orgentis Chemicals GmbH | +49 39482 355 | Germany | |
| Ovelle Pharmaceuticals | 353-42-9332305 | IRELAND | |
| Olympic Star Pharmaceutical Co.,Ltd | 86-755-25310416 | China | |
| octagon chemicals limited | 8613250843579 | China | |
| Onwon Trading Limited | +852 2757 7569 | Hong Kong | |
| OK Scientific Ltd. | 86 21 5858 0732 | China | |
| OLON SPA | Italy | ||
| Olainfarm | 37-1-67013705 | LATVIA | |
| OTAVA Ltd. | 416 305 9979 (Canada) | Ukraine | |
| Olymchemical Ltd. | +86 21 20221339 | China | |
| Oy Arbonova Ab | Finland | ||
| OMEGACHEM INC. | 418 837-4444 | Canada | |
| Orthodox Union | 1-212-5634000 | United States |