He served as Director and later as Joint Secretary in charge of the Consular, Passports and Visa division of the Ministry of External Affairs at New Delhi. He supervised computerization of all passport offices in India, laid foundation for amendment of the Passport Act which paved the way for modernisation of all passport offices, contributed to induction of More Secured Passports.  With approval of Shri IK Gujral, the then External Affairs Minister delegated powers to all Indian missions and Posts abroad to issue multiple entry visas valid up to five years. Earlier missions could issue only short term visas valid up to six months.

Even before retirement from IFS articles promoting Social harmony, samarasata among Hindus were contributed by Ambassador OP Gupta to newspapers:

• • 1. 1. ‘In Rig Veda, some facts about Sati’ [4 October 2002, Indian Express]
       2. ‘Caste in the Wrong Mould’ [17 January 2003, Indian Express]
       3. “Widows do not have to burn” [22 October 2002, The Asian Age]
       4. ‘It Has All been said before’ [21 May 2005, Indian Express] [Vedic Rights of Hindu Women]

ORGANISER weekly also carried articles promoting Social harmony among Hindus:

• 1. 1. Rig Veda Prohibits Widow Burning [3 November 2002]
     2. Religious Conversions are futile; Social Reforms in Hinduism Need of the Hour [12 January 2003]
     3. Rig Veda Prohibits Casteism among Hindus.[16 March 2003]
     4. Vedas, Beef and Medical Sciences.[25 January 2005]

After retirement Ambassador OP Gupta contributed gratis about 45 articles to the Organiser weekly on foreign policy, international affairs and domestic electoral, political and economic matters including an article captioned “MODI a victim of left- Islamist witchhunt: Facts reved a different story ” Oganiser “18th April 2010“

In 2014 his book Defining Hindutva was released by Shri Mohan Bhagwat ji, RSS Chief.

After the retirement Ambassador Gupta used to deliver lectures on international relations to civil services candidates at the Samkalp and also chaired mock interviews. He was awarded the 2011 Guru Samman by the Samkalp.

Since 2003 the world famous  www.hinduwisdom.info is carrying five articles contributed by Ambassador OP Gupta.

During Finland days sify.com also carried articles of Ambassador Gupta including interactive Q & A series.