- The First Official Meeting of the OWTU July 15, 1937 The OWTU was formally established, at its Founding Conference on July 25, 1937
- The OWTU was officially registered as a Trade Union on September 15, 1937
- In July 1937, Adrian Cola Rienzi became the first President General of the OWTU, a position he held until the year 1943.
- The first Annual Conference of Delegates was held in 1939
- In 1939 Butler was made Chief Organizer of the OWTU. In the same year he was also expelled from the Union.
- John F.F. Rojas succeeds Rienzi as President General. Rojas led the Union from 1943 to 1962.
- The OWTU negotiated its first Industrial Agreement in 1945. This first historic agreement was entered into between the OWTU and an umbrella group of oil companies known as the Oilfields Employers Association of Trinidad.
- A Disturbance Allowance was first secured for workers in 1952.
- The first official strike in the OWTU’s history was called in 1960 at Texaco. Coming out of this strike the Union was able to secure a reduction in the working hours to 44 hours per week.
- George Weekes was elected as President General in 1962.
- On June 25, 1962 for the first time in the Union’s history each member was entitled to vote for the leadership of his choice (‘one-man-one-vote’).
- At the 27th Annual Conference of Delegates, held in January 1967, Rule No.2 was amended to allow workers from outside the oil industry to become members of the OWTU. This move was initiated by workers at TCL who had expressed their desire to join the OWTU, but who were blocked by the existing Rule No.2. Following the amendments, workers at TCL, Fed Chem, Dunlop and T&TEC, amongst others became represented by the OWTU. The OWTU was now transformed from a sectoral union to a general union.
- In 1969 Tubal Uriah ‘Buzz’ Butler was officially brought back into the fold of the OWTU. He was made a life member and awarded the Union’s highest honour – The Labour Star.
- During the 1970 Black Power Uprisings the Williams’ Government declared a State of Emergency on April 21, 1970. During this State of Emergency, the then President General, George Weekes and other leaders of the OWTU were imprisoned.
- In November 1971 a second state of emergency was declared and once again Weekes and other Union officers were arrested.
- In 1971, a life size statue of Butler was erected at the Fyzabad Branch Hall.
- Errol K. McLeod became the Union’s fourth President General in June, 1987, upon the retirement of George Weekes.
- Ancel Roget became the President General in June, 2008 when Errol McLeod retired after serving as President General for twenty-one years.