Chemical, Oil & Gas Company Index - O
- O T M Consulting Ltd - Guildford
- O'Neill and Co Ltd - Glasgow
- Oak Industrial Supplies - Sutton in Ashfield
- Oakmere Technical Services Ltd. - Chester
- Oakville Ltd. - London
- Oamps (U K) Ltd. - Esher
- Ocean Corporate Hygiene - Sunbury on Thames
- Ocean Technical Systems Ltd. - Sutton
- Oceaneering International Services Ltd. - Aberdeen
- Oceanscan Ltd - Aberdeen
- Octavius Hunt Ltd. - Bristol
- Oel-Held (Uk) Ltd. - Denbigh
- Oil Analysis Services Ltd - Sevenoaks
- Oil and Gas Associates Ltd - Dunstable
- Oil and Gas Project Consultants Ltd - Woking
- Oil Direct - Dromore
- Oil Inventions Ltd. - Walsall
- Oil Plus Ltd - Newbury
- Oil Pollution Environmental Control Ltd - Batley
- Oil Recruitment - Knutsford
- Oil States Klaper Ltd. - Bathgate
- Oil States MCS Ltd - Barrow in Furness
- Oil Technics Ltd. - Montrose
- Oilandgasjobvacancies.com - Caerphilly
- Oilequipprocurementserve Ltd. - London
- Oilfield Production Support Group Ltd. - Aberdeen
- Oilfield Solutions Ltd. - Inverurie
- Oilfield Tool Inspection Ltd. - Banchory
- Oilsearch Plc - Malvern
- Old Hall Performance Ltd. - Birmingham
- Oleo Solutions Ltd - York
- Oliver Valves Ltd. - Knutsford
- Omega Data Services Ltd - Aberdeen
- Omega Resistance Wire - Potters Bar
- Omega Resources Ltd - Alloa
- Omex Agriculture Ltd. - Lincoln
- Omv (U K ) Ltd. - London
- Omv (U K ) Ltd. - London
- One Brand Group - Bristol
- One for Instrumentation Ltd - Congleton
- Online Lubricants Ltd - Barking
- Onyvax Ltd. - London
- Onyx Scientific Ltd. - Sunderland
- OPM Furniture Ltd - London
- Optima Solutions Uk Ltd. - Aberdeen
- Optimus (Aberdeen) Ltd - Aberdeen
- Orange Chemicals Ltd. - Winchester
- Orion Valves Ltd - Wimborne
- Outreach Ltd - Falkirk
- Oxy - Wax Ltd. - Billingham