There are 1,885 titles that begin with the letter O
- Open geospatial data, software and standards. (ISSN: 2363-7501)
- Open health data. (ISSN: 2054-7102)
- Open health. (ISSN: 2544-9826)
- Open heart. (ISSN: 2398-595X, 2053-3624)
- Open information science (ISSN: 2451-1781)
- The open inorganic chemistry journal. (ISSN: 1874-0987)
- Open Insight (ISSN: 2007-2406)
- Open journal for legal studies. (ISSN: 2620-0619)
- The open journal of astrophysics (ISSN: 2565-6120)
- Open Journal of Biophysics. (ISSN: 2164-5388, 2164-5396)
- Open journal of bioresources. (ISSN: 2056-5542)
- Open journal of cardiovascular surgery. (ISSN: 1179-0652)
- Open journal of humanities. (ISSN: 2612-6966)
- Open Journal of Implant Dentistry : OJID ; official journal of the South African Society of Dental Implantology (SASDI) (ISSN: 2226-4507)
- Open journal of mathematical optimization. (ISSN: 2777-5860)
- The open journal of occupational therapy. (ISSN: 2168-6408)
- Open journal of psychiatry & allied sciences. (ISSN: 2394-2053, 2394-2061)
- Open learning. (ISSN: 0268-0513, 1469-9958)
- Open Library of Humanities (ISSN: 2056-6700)
- Open life sciences. (ISSN: 2391-5412)
- Open Linguistics. (ISSN: 2300-9969)
- The open macromolecules journal. (ISSN: 1874-3439)
- Open material sciences (ISSN: 2544-7300)
- The open materials science journal. (ISSN: 1874-088X)
- Open mathematics. (ISSN: 2391-5455)
- The open medical informatics journal. (ISSN: 1874-4311)
- The open medicinal chemistry journal. (ISSN: 1874-1045)
- Open medicine : a peer-reviewed, independent, open-access journal. (ISSN: 1911-2092)
- Open medicine. (ISSN: 2391-5463)
- The open microbiology journal. (ISSN: 1874-2858)
- Open military studies. (ISSN: 2545-3254)
- Open mind : discoveries in cognitive science. (ISSN: 2470-2986)
- The open mineralogy journal. (ISSN: 1874-4567)
- The open nanoscience journal. (ISSN: 1874-1401)
- The open neuroimaging journal. (ISSN: 1874-4400)
- The open neurology journal. (ISSN: 1874-205X)
- The open nursing journal. (ISSN: 1874-4346)
- The open ophthalmology journal. (ISSN: 1874-3641)
- The open organic chemistry journal. (ISSN: 1874-0952)
- The open orthopaedics journal. (ISSN: 1874-3250)
- Open Philosophy (ISSN: 2543-8875)
- The open physical chemistry journal. (ISSN: 1874-0677)
- Open physics. (ISSN: 2391-5471)
- Open political science (ISSN: 2543-8042)
- Open praxis. (ISSN: 1369-9997, 2304-070X)
- Open psychology. (ISSN: 2543-8883)
- Open quaternary. (ISSN: 2055-298X)
- Open research Africa. (ISSN: 2752-6925)
- Open research Europe. (ISSN: 2732-5121)
- Open respiratory archives. (ISSN: 2659-6636)
- The open respiratory medicine journal. (ISSN: 1874-3064)
- Open review of educational research. (ISSN: 2326-5507)
- The open rheumatology journal. (ISSN: 1874-3129)
- Open rivers : rethinking the Mississippi. (ISSN: 2471-190X)
- OPEN ROAD (ISSN: 0048-1947)
- Open screens (ISSN: 2516-2888)
- Open Shelf (ISSN: 2368-1837)
- Open Solutions Inc. MarketLine Company Profile
- The open source business resource (ISSN: 1913-6102)
- The open spectroscopy journal. (ISSN: 1874-3838)
- Open statistics. (ISSN: 2657-3601)
- Open Text Corporation MarketLine Company Profile
- Open theology. (ISSN: 2300-6579)
- The open thermodynamics journal. (ISSN: 1874-396X)
- The open toxicology journal. (ISSN: 1874-3404)
- The open translational medicine journal. (ISSN: 1876-3995)
- Open veterinary journal. (ISSN: 2226-4485, 2218-6050)
- Open veterinary science. (ISSN: 2544-8951)
- The open virology journal. (ISSN: 1874-3579)
- Open-Source-Jahrbuch
- Open. (ISSN: 1530-9495)
- Opening writing doors. (ISSN: 2322-9187, 1692-7850)
- Openings : studies in book art. (ISSN: 2326-0157)
- OpenNano (ISSN: 2352-9520)
- OpenPhysio. (ISSN: 2631-8369)
- Opera : observatorio de políticas, ejecución y resultados de la administración pública (ISSN: 1657-8651, 2346-2159)
- Opera Canada. (ISSN: 0030-3577)
- Opera corcontica. (ISSN: 0139-925X, 1803-1412)
- Opera historica : časopis pro dějiny raného novověku. (ISSN: 1805-790X, 2694-720X)
- The Opera journal. (ISSN: 0030-3585)
- Opera news. (ISSN: 0030-3607, 1938-1506)
- The opera quarterly (ISSN: 0736-0053, 1476-2870)
- Opera Slavica. (ISSN: 1211-7676, 2336-4459)
- Opera Software ASA MarketLine Company Profile
- Operant subjectivity. (ISSN: 0193-2713)
- Operating systems review. (ISSN: 0163-5980, 1943-586X)
- The operating theatre journal. (ISSN: 1747-728X)
- Operation EUFOR TCHAD/RCA and the European Union's Common Security and Defense Policy
- Operation Iraqi Freedom & the New Iraq: Insights & Forecasts
- Operational research in engineering sciences : theory and applications. (ISSN: 2620-1607, 2620-1747)
- Operational research quarterly. (ISSN: 0030-3623, 2397-5334)
- Operational research quarterly. (ISSN: 1473-284X, 2397-5350)
- Operational research. (ISSN: 1109-2858, 1866-1505)
- Operational Risk & Regulation (ISSN: 2045-0672)
- Operations management education review. (ISSN: 1649-7082, 2044-4567)
- Operations management research : advancing practice through research. (ISSN: 1936-9735, 1936-9743)
- Operations management. (ISSN: 1529-5648)
- Operations report / Franchise Tax Board
- Operations research and decisions. (ISSN: 2081-8858)
- Operations research for health care. (ISSN: 2211-6923, 2211-6931)