| 1 | NOX | North Express AB | Callsign: North Express, Formerly Fly Logic Malmo AB. | S | AVCODES |
| 2 | NOX | Cities Service Oil Co. | added 1/1962; eliminated 4/1962 | | NAKINA |
| 3 | NOX | Arkansas Fuel Oil Corp. | added 10/1958; 4/1961; eliminated 1/1962 | | NAKINA |
| 4 | NOX | National Oil Co. | 7/1937-10/1957; eliminated 10/1958 | | NAKINA |
| 5 | NOX | National Oil Co., Inc. | 8/1920-7/1935 | | NAKINA |
| 6 | NOX | National Oil Co. | 4/38-10/57; eliminated 10/58 | | NRHS |
| 7 | NOX | Arkansas Fuel Oil Corp. | added 10/58; 4/61; eliminated 1/62 | | NRHS |
| 8 | NOX | Cities Service Oil Co. | added 1/62; eliminated 4/62 | | NRHS |
| 9 | NOX | CITIES SERVICE OIL CO. [ARKANSAS FUEL OIL CORP., NATIONAL OIL CO.] | | | PWRC |
| 10 | NOX | National Oil Co. | | USA | TRAFFIC |
| 11 | NOXC | NOX-CHEM TRANSPORTATION INC | | | SCAC3 |
| 12 | NOXL | NETCO TRANSPORT LLC | | | SCAC4 |
| 13 | NOXN | NINE ONE SIX TWO NINE | | | SCAC4 |
| 14 | NOXQ | NORTH EXPRESS CO | | | SCAC3 |
| 15 | NOXU | LEEDEN NATIONAL OXYGEN LTD | | SGP | BIC |
