TNO may refer to:
- Franco-Ténois, the widespread community of francophones who reside in the Northwest Territories
- Netherlands Organisation for Applied Scientific Research, an independent research organization in the Netherlands
- Tamarindo Airport, a private airport that serves Tamarindo, Costa Rica
- Tête nucléaire océanique, a French thermonuclear warhead
- Thai National Observatory, part of the National Astronomical Research Institute of Thailand
- TNO intestinal model, systems mimicking the digestive tract
- Trans-Neptunian object, any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune
- Texas and New Orleans Railroad, a railroad in Texas and Louisiana. Was bought by Southern Pacific in 1881, and merged with Southern Pacific in 1961.
