RTD may refer to:
- In broadcasting
- Radio Tanzania Dar es Salaam, the state radio broadcasting organisation of Tanzania
- Radiodiffusion Télévision de Djibouti
- RT Documentary
- In science and technology
- Real-Time Dispatching, a software component
- Residence Time Distribution
- Research & Technical Development
- Resonant tunnelling diode, a device using the quantum effect and the negative differential resistance
- Resistance temperature detector, also called resistance thermometer
- Round trip delay
- RTD info, a European science magazine
- In transportation
- Regional Transportation District, a mass transit management system based in Denver, Colorado, United States
- Sacramento Regional Transit District in California, United States
- San Joaquin Regional Transit District of Stockton, California
- Southern California Rapid Transit District, now known as the Los Angeles County Metropolitan Transportation Authority
- Malaysian Road Transport Department
- In other
- Right to Die, the right to commit suicide
- Ready to drink, an alcoholic or non-alcoholic beverage that requires no preparation before it can be consumed
- Russell T Davies, Welsh screenwriter and television producer most notable for reviving Doctor Who
- "Remember the day", internet/chat slang, used to note important occasions.
- Referee technical decision in boxing
- Richmond Times-Dispatch, the primary daily newspaper in Richmond, Virginia
- Rtd., abbreviation for retired