[4] O'Brien was educated at Cardinal Langley Grammar School in Middleton, Greater Manchester and the University of Liverpool where he was awarded a Bachelor of Science degree in 1975.

[10] He was an advocate of communicating science to a wider audience and gave popular talks – usually on nanotechnology – including Café Scientifique and school lectures.

[11] O'Brien was passionate about international development and over two decades he worked tirelessly to encourage excellence in teaching and learning across Africa, with very strong ties to the University of Zululand.

O'Brien was elected a Fellow of the Royal Society (FRS) in 2013, his certificate of election reads: Paul O'Brien is distinguished for his many original contributions to chemistry and materials science, notably in the use of novel molecularly defined precursors from which to prepare important functional electronic or optical materials in well-defined forms.

He has shown how relatively stable compounds can be used to prepare high quality functional materials, and developed improved methods to convert precursors into useful functional products, devising and refining ways by which nanoparticles syntheses can be controlled within the size limits require for device use[14]In 2016, O'Brien was appointed a Commander of the Most Excellent Order of the British Empire (CBE) in the 2016 New Year Honours for services to science and engineering,[15] received the RSC Longstaff Prize[12] and was elected a Fellow of the Royal Academy of Engineering (FREng).