| RDS | Radio data system |
| RDT | Real Data Transport |
| Re | Rhenium |
| RE | Rare Earths |
| Ref | Reference; Reference Voltage |
| RegTP | Regulierungsbehörde für Telekommunikation und Post |
| REL | Recommended Exposure Limit; Rights Expression Language |
| REM | Reflection Electron Microscopy |
| RESSFOX | REcessed Sealed Sidewall Field OXidation |
| Rf | Rutherfordium |
| RF | Radio Frequency; Resonance Frequency |
| RfC | Request for Comment |
| RFI | Request For Information; Radio Frequency Interference |
| RFIC | Radio Frequency Integrated Circuit |
| RFICP | Radio Frequency ICP |
| RFID | Radio Frequency IDentification |
| RFM | Radio frequency monitoring |
| RFO | Restricted flow orifice |
| RfP | Request for Plan; Request for Proposal |
| RFP | Radio Frequency Probe |
| RFQ | Request for quote |
| RFS | Regardless of Feature Size |
| RFT | Resistive Force Theory; Request For Tender |
| RGA | Residual gas analysis |
| Rh | Rhodium |
| RH | Relative humidity |
| RHEED | Reflection High-Energy Electron Diffraction |
| RHET | Resonant Hot-tunnelling Electron Transistor |
| RIBE | Reaction Ion Beam Etching |
| RIE | Reactive Ion Etching |
| RIM | Read-in mode |
| RISC | Reduced Instruction Set Computer/Computing |
| RIST | Rule induction and statistical testing |
| RKKY | Ruderman-Kittel-Kasuya-Yoshida |
| RLE | Windows or CompuServe RLE image format |
| RLI | Resist LIthography |
| RMA | Rosin Mildly Activated |
| RMI | Remote Method Invocation |
| RMOS | Refractory Metal-Oxide Semiconductor |
| RMS | Root Mean Square; Recipe Management Standard |
| RMSEP | Root Mean Square Error of Prediction |
| RMTF | Recipe Management Task Force |
| Rn | Radon |
| RNN | Recurrent Neural Network |
| RO | Reverse Osmosis |
| ROC | Remote Object Communications |
| ROE | Return On Equity |
| ROI | Return On Investment |
| ROM | Read-Only Memory; Rough Order of Magnitude |
| ROS | Record-On-Silicon |
| ROX | Run Of eXperiments |
| RPC | Remote Procedure Call |
| RPM | Revolutions Per Minute |
| RPR | Resilient Packet Ring |
| RQ | Reportable Quantity |
| RR | Removal Rate |
| RRMSEP | Relative Root Mean Square Error of Prediction |
| RS232 | Norm for serial transmission |
| RSE | Reactive sputter etch |
