- Born: 01-02-1811 Amsterdam, the Netherlands.
- Married: 1835 Aletta Maria Waller (1810-1898).
- Son: Hendrik Jan de Marez Oyens (1843-1911).
- Lived at the Keizersgracht 315, Amsterdam, the Netherlands. House Hendrik Jan de Marez Oyens.
- Also member of the board of the Rembrandt House, vice president Maatschappij tot Bevordering der Toonkunst etc.
- Banker, member of the board of the Netherlands Bible Society; married in 1835 with Aletta Maria Waller (1810-1898), member of the Board of the Women's Association to the Visits of Condemned Women in the Cellular Prison
- Died: 19-03-1883 Amsterdam, the Netherlands. Aged 71.
Gustav Mahler visited him in Year 1904.
Oijens (also: Oyens, the Marez Oijens, the Marez Oyens and Weckherlin de Marez Oijens) is a Dutch banker family that also produced directors and artists.