Barend Jacobus du Plessis was born on 19 January 1940 in Johannesburg to Martie and Jan Hendrik du Plessis. He was the eldest of three children and grew up in Boksburg. Du Plessis attended Baanbreker Primary School and Voortrekker High School.
After matriculating in 1956 he obtained his B.Sc. degree in 1960 at Potchefstroom University of Higher Christian Education and in 1961 also completed his Transvaal Higher Education Diploma. During his studies du Plessis played an active role in the Transvaal Teacher Training College Union. Although this organisation concerned itself with student and educational rather than political issues it can be seen as his first foray into the political arena. He was elected as Chairman of the Students’ Representative Council, which enabled him to travel abroad to Holland, Germany and Belgium and meet with other student leaders.
In 1962 du Plessis started teaching mathematics at the Hoër Seunsskool Helpmekaarin Johannesburg, as well as at the Johannesburg Technical College. Eventually he was employed by the South African Broadcasting Corporation (SABC) as administrative officer to the Chief Engineer and was promoted to the new data processing department where he received training in computer technology. His career at the SABC advanced further and he was transferred to the office of the Director General as administrative secretary.
Following his resignation from the SABC in 1968 he joined the international computer company, IBM, where he was employed until 1974. Between 1968 and 1974 he received training in banking and finance and attended the IBM Graduate School of Banking in Princeton in the United States of America.
Gastrow, S. (1987). Who’s Who in South African Politics, no 2, Johannesburg: Ravan.|Joyce, P. (1999). A Concise Dictionary of South African Biography, Cape Town: Francolin.|Mail & Guardian Online. 3 December 2004.