| 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 |
| ILS | Intracavity Laser Spectroscopy |
| IM | Integrated Model; Instant Messaging |
| IM4DTTV | Integrated Modem for DTTV |
| IMD | InterMetal Dielectric |
| IMG | GEM Paint image format |
| IMMA | Ion Microphobe Mass Analysis |
| IMR | Integrated Model Repository |
| IMS | Ion Mobility Spectroscopy; Intelligent Manufacturing System |
| IMT | International Mobile Telecommunications |
| In | Indium |
| InAs | Indium Arsenide |
| INCAMS | Individual cassette manufacturing system |
| InGaAs | Indium Gallium Arsenide |
| InGaAsP | Indium Gallium Arsenide Phosphide |
| InGaN | Indium Gallium Nitride |
| InP | Indium Phosphide |
| INS | Inelastic Neutron Scattering |
| InSb | Indium Antimonide |
| I/O | Input/Output |
| IOT | Inductive Output Amplifier |
| IP | Intellectual Property; Internet Protocol |
| I-PAL | Improved PAL |
| IPAT | ISDN Primary-Rate Access Transceiver |
| IPC | Institute for interconnecting and Packaging ICs; International Press Telecommunications Council |
| IPL | Ion Projection Lithography |
| IPM | Inches Per Minute |
| IPO | Initial Public Offering |
| IPR | Intellectual Property Rights |
| IPRM | Indium Phosphide Related Materials |
| IPT | Ideal Process Time |
| IPTC | International Press and Telecommunications Council |
| Ir | Iridium |
| IR | InfraRed |
| IRAS | Infrared Reflection-Absorption Spectroscopy |
| IRFPA | IR Focal Plane Array |
| IRIS | Imaging of Radicals Interacting with Surfaces |
| IRM | Ion Rate Monitoring; Isothermal Remnant Magnetization |
| IRN | Internal Recurrent Neural network |
| IRONMAN | Improving Reliability Of New Machines At Night |
| IRPC | ISDN Remote Power Controller |
| IRS | InfraRed Spectroscopy |
| IRTC-1 | Interconnect Reliability Test Chip-1 |
| IS | Information Systems; Interface Specifications; Integrated Systems |
| ISA | Instrumentation Society of America |
| ISAC | ISDN Subscriber Access Controller |
| ISAN | International Standard Audiovisual Number |
| ISBN | International Standard Book Number |
| ISC | Industry Steering Council; Inter System Crossing |
| ISD | Interface State Density |
| ISDB | Integrated Services Digital Broadcasting |
| ISDN | Integrated Services Digital Network |
| ISE | Integrated Solid Effect |
| ISEM | Inspection/review Specific Equipment Model |
| ISHM | International Society for Hybrid Microelectronics |
| ISM | Industrial, Scientific & Medical band; Inductor Super Magnetron |
| ISMA | Internet Streaming Media Alliance |
| ISO | International Standards Organization |
| ISP | Interface Strain Parameter; Internet Service Provider |
| J2EE | Java 2 Enterprise Edition |
| J2SE | Java Level 2 Standard Edition |
| JAAS | Java Authenticationand Authorization Service |
| JADE | Joint Audio Decoder Encoder |
| JAR | Java Archive |
| JAXP | Java API for XML |
| JAXR | Java API for XML Registries |
| JDBC | Java Database Connectivity |
| JDP | Joint Development Program |
| JEDEC | Joint Electron Device Engineering Council (aka. Joint Electronics Design Engineering Council) |
| JEIDA | Japanese Electronic Industries Development Association |
| JESSI | Joint European Submicron Silicon |
| JFET | Junction FET |
| JFIF | JPEG/JPG compliant image format |
| JIC | Joint Industrial Council |
| JIT | Just-In-Time |
| JJT | Josephson Junction Transistor |
| JMS | Java Message Service |
| JPG | JPEG/JFIF compliant image format |
| JPEG | Joint Photographic Experts Group (aka JPG) image format |
| JQP | Josephson Quasi Particle |
| JSNM | Japan Society of New Metals |
| JSP | JavaServer Pages |
| JT | Jahn-Teller |
| JTA | Java Transaction API |
| JTAG | Joint Test Action Group (part of IEEE) |
| JVM | Java Virtual Machine |