Electronics Company Index - O
- Oakmoor - London
- Oakmount Control Systems Ltd - Plymouth
- Oakwade Ltd - Hartlepool
- Oasis Electronics Ltd - Milton Keynes
- Oasis Ltd - Slough
- Ocean Grove Developments Ltd - Reading
- Ocean Systems Ltd. - Fleet
- Octec Ltd - Bracknell
- ODU (UK) Ltd - Loughborough
- OEM Automatic Ltd - Leicester
Offshore Electronics Ltd - Guernsey
- Og Sport Ltd. - Banbury
- Ogier Electronics Ltd - St Albans
- Ohgon Electronics - Canvey Island
- Ohm Uk Ltd - Knutsford
- Ohmega Ltd. - New Milton
- OK International Ltd - Chandlers Ford
- Oki (U K) Ltd. - Glasgow
- Oki Europe Ltd. - Egham
- Oki Systems (Uk) Ltd. - Slough
- OKW Enclosures Ltd - Fareham
- Oldham Lighting Ltd. - Leatherhead
Ole Wolff Electronics Ltd - Bedford- Olmec Advanced Materials Ltd/Surelight - Sheffield
- Olson Electronics Ltd - Stanmore
- Olympus Automation Ltd. - Peterborough
- Olympus Uk Ltd. - London
- Omega Calibration Laboratories Ltd - Chesterfield
- Omega Engineering Ltd - Manchester
- Omega Research Ltd - Ely
- Omega Resistance Wire - Potters Bar
- Omi TV Services - Stevenage
- Omicron Ltd. - Ilford
- Omiran Ltd. - Bury St Edmunds
- Omitec Instrumentation Ltd - Devizes
- Omni Sensors and Transmitters Ltd - Leamington Spa
- Omnia H V & Rail Ltd. - Uttoxeter
- Omniflex (U K) Ltd. - Stockport
- Omnitest Ltd. - Ferndown
- Omron Electronics Ltd - Milton Keynes
- On Board Surface Mount Assembly Ltd - Darwen
- On Time Communications Ltd - High Wycombe
- Onclick Ltd - Tonbridge
- One North East Development Board - Newcastle upon Tyne
- One Way Circuits Ltd - Norwich
- ONE-SAT (a division of Open Networks Engineering Ltd) - Bishops Stortford
- Onyx Holdings Ltd - South Petherton
- OP-TEC Systems Ltd - Telford
- Opal Group Ltd - Manchester
- Opas I T Ltd. - London
- OpenBet Retail Ltd - Guildford
- Optex (Europe) Ltd - Maidenhead
- Optical Filters Ltd. - Thame
- Optical Technology Training Ltd - Skipton
- Optical Test and Calibration Ltd - Bradford
- Opticon Ltd. - Luton
- Opticus - Glasgow
- Optikinetics Ltd - Luton
- Optilan (Uk) Ltd. - Coventry
- Optime Lighting Ltd. - Hitchin
- Optimim Ltd. - Llandysul
- Option Technologies Europe Ltd. - Rossendale
- Optisense Ltd. - Horsham
- Optivision (Yorkshire) Ltd. - Ossett
- Optocap Ltd. - Livingston
- Optoma Europe Ltd. - Watford
- Optosci Ltd. - Glasgow
- Oracle Components Ltd - Harlow
- Oracle Vision Ltd - Wakefield
- Orange Instruments Ltd. - Northampton
- Orbik Electronics Ltd. - Walsall
- Orbit Research Ltd - Rugby
- Orbital Epos Systems Ltd - Warminster
- Orchard Process Controls - Brixham
- Oriel Systems Ltd - Chippenham
- Orion Control Systems Ltd. - Swadlincote
- Orion Devices Ltd. - Norwich
- Orion Projects Ltd. - Saltash
- Orlight Ltd - Potters Bar
- Ormiston Wire Ltd - Isleworth
- Osborne and Collins - Walton on Thames
- Osco Ltd - Bletchley
- Oshino Lamps UK Ltd - Nottingham
- Ossett Industrial Projects Ltd. - Ossett
- Oticon Ltd. - Hamilton
- Otodynamics Ltd. - Hatfield
- Otter Controls Ltd. - Buxton
- Outram Research Ltd - Chichester
- Outsource Electronics Ltd. - Havant
- Oval Automation Ltd - Bognor Regis
- Ovation Systems Ltd - Thame
- Overcare Ltd. - Bournemouth
- Overseas Medical Supplies (U K) Ltd. - London
- Oxford Electronics - Oxford
- Oxford Electronics Ltd. - Alton
- Oxford Instruments NanoAnalysis - High Wycombe
- Oxford Instruments Plasma Technology Ltd. - Bristol
- Oxford Instruments Superconductivity Ltd. - Abingdon
- Oxford Lasers Ltd - Didcot
- Oxley Developments Company Ltd - Ulverston
- Oyster Terminals Uk Ltd. - Coventry