| 1 | HOK | Hokuetsu Express Co., Ltd. | | J | TRAFFIC |
| 2 | HOKAN | Hokutetsu Kanazawa Bus | Subsidiary of the Hokuriku Railroad | J | TRAFFIC |
| 3 | HOKC | HASKO TRUCKING INC | | | SCAC4 |
| 4 | HOKG | HARCO TRUCKING LLC | | | SCAC4 |
| 5 | HOKKB | Hokkaido Bus Co. | | J | TRAFFIC |
| 6 | HOKKO | Hokko Kanko Bus | | J | TRAFFIC |
| 7 | HOKL | HOMELAND TRUCK LINES | | | SCAC4 |
| 8 | HOKRD | Hokkaido Railway Department | | J | TRAFFIC |
| 9 | HOKS | Hokuso Railway | | J | TRAFFIC |
| 10 | HOKU | Hokuetsu | | J | TRAFFIC |
| 11 | HOKX | Occidental Chemical Corp. | added 1/1992; 1/1994-7/2005 | | NAKINA |
| 12 | HOKX | Occidental Chemical Corp., Electrochemicals & Specialty Products | added 10/1989; eliminated 1/1992 | | NAKINA |
| 13 | HOKX | Occidental Chemical Corp., Electrochemicals, Detergents & Specialty Products | added 1/1988; eliminated 10/1989 | | NAKINA |
| 14 | HOKX | Occidental Chemical Corp., Electrochemicals, Detergent & Specialty Products Group | added 7/1987; eliminated 1/1988 | | NAKINA |
| 15 | HOKX | Occidental Chemical Corp., Industrial & Specialty Chemicals | added 7/1984; eliminated 7/1987 | | NAKINA |
| 16 | HOKX | Occidental Chemical Corp., Hooker Industrial & Specialty Chemicals | added 10/1982; eliminated 7/1984 | | NAKINA |
| 17 | HOKX | Hooker Chemicals and Plastics Corp. | added 7/1974; 1/1975-1/1980; eliminated 10/1982 | | NAKINA |
| 18 | HOKX | Hooker Chemical Corp. | added 10/1958; 4/1961-4/1970; eliminated 7/1974 | | NAKINA |
| 19 | HOKX | Hooker Electrochemical Co. | 7/1930-10/1957; eliminated 10/1958 | | NAKINA |
| 20 | HOKX | Hooker Electrochemical Co. | 4/38-10/57; eliminated 10/58 | | NRHS |
| 21 | HOKX | Hooker Chemical Corp. | added 10/58; 4/61-4/70 | | NRHS |
| 22 | HOKX | Hooker Chemicals and Plastics Corp. | 1/75-1/80; eliminated 10/82 | | NRHS |
| 23 | HOKX | Occidental Chemical Corp., Hooker Industrial & Specialty Chemicals | added 10/82; eliminated 7/84 | | NRHS |
| 24 | HOKX | Occidental Chemical Corp., Industrial & Specialty Chemicals | added 7/84; eliminated 7/87 | | NRHS |
| 25 | HOKX | Occidental Chemical Corp., Electrochemicals, Detergent & Specialty Products Group | added 7/87; eliminated 1/88 | | NRHS |
| 26 | HOKX | Occidental Chemical Corp., Electrochemicals, Detergents & Specialty Products | added 1/88; eliminated 10/89 | | NRHS |
| 27 | HOKX | Occidental Chemical Corp., Electrochemicals & Specialty Products | added 10/89; eliminated 1/92 | | NRHS |
| 28 | HOKX | Occidental Chemical Corp. | added 1/92; 1/94-7/2000 | | NRHS |
| 29 | HOKX | HOOKER INDUSTRIAL & SPECIALTY CHEMICALS (OCCIDENTAL CHEMICAL CORP.) | | | PWRC |
| 30 | HOKX | Hooker Chemical (Occidental Chemical Corporation) | | | RSRV |
| 31 | HOKX | OCCIDENTAL CHEMICAL CORP., AGRICULT | | | SCAC4 |
| 32 | HOKX | Occidental Chemical Corporation | | USA | TRAFFIC |