| I | Iodine |
| I2C | Intra Integrated Circuit |
| I2L | Integrated injector logic |
| I300I | International 300 mm Initiative |
| IAP | Imaging Atom Probe |
| IBAE | Ion Beam Assisted Etching |
| IBC | ISDN Burst Controller |
| IBD | Ion Beam Deposition |
| IBE | Ion Beam Etching; Isoelectronic Bound Exciton |
| IC | Integrated Circuit; Investment Council; Ion Chromatography |
| ICA | Isotropically Conductive Adhesive |
| ICAM | Integrated CAM |
| ICAP | Inductively-Coupled Argon-Plasma (spectrometry) |
| ICC | ISDN Communication Controller |
| ICCG | InComplete Conjugate Gradient |
| ICE | In-Circuit Emulator; Information and Content Exchange Format |
| ICMS | Integrated Circuit Measurement System |
| ICP | Inductively-Coupled Plasma |
| ICP-AES | Inductively-Coupled Plasma Atomic Emission Spectroscopy |
| ICP-MS | Inductively-Coupled Plasma Mass Spectrometry |
| ICT | Ideal Cycle Time; In-Circuit Test |
| IDA | Interchange of Data between Administrations |
| IDC | Insulation-Displacement Connection |
| IDDQ | Direct Drain Quiescent Current |
| IDEA | International Data Encryption Standard |
| IDEAL | Initiating, Diagnosing, Establishing, Acting, Leveraging |
| IDEAlliance | International Digital Enterprise Alliance |
| IDEC | ISDN D-Channel Exchange Controller |
| IDL | Interface Definition Language |
| IDLH | Immediately Dangerous to Life or Health |
| IDS | Interactive Diagnostic System |
| IEA | Ion Energy Analysis |
| IEC | Infused Emitter Coupling; International Electrotechincal Commission; ISDN Echo Cancellation Circuit; International Engineering Consortium |
| IECQ | International Electronic Component Qualification system |
| IEDF | Ion Energy Distribution Function |
| IEEE | Institute of Electrical and Electronics Engineers |
| IEF | Imaging Energy Filter |
| IEPC | ISDN Enhanced Power Controller |
| IEPS | International Electronics Packaging Society |
| IERN | Internal-External Recurrent Neural network |
| IETF | Internet Engineering Task Force |
| IF | Interface; Intermediate frequency |
| IFF | If and only if; Commodore Amiga image format |
| IGBT | Insulated Gate Bipolar Transistor |
| IGES | Integrated Graphics Exchange System |
| IGFET | Insulated-Gate Field-Effect Transistor |
| IGMP | Internet Group Multicast Protocol |
| IHPC | ISDN High-Voltage Power Controller |
| IHT | Ideal Handler Time |
| iHTML | inline HTML |
| II | Ion Implant (also I2) |
| IIC | Intra Integrated circuit |
| IIOP | Internet Inter-ORB Protocol |
| ILB | Inner Lead Bond |
| ILD | InterLevel Dielectric; InterLayer Dielectric |
| ILM | Integrated Laser Modulator; Instrumental Landing System |
| ILS | Intracavity Laser Spectroscopy |
