A finite group G is said to be (2, 3, t)-generated, if it is a quotient of triangle group T (2, 3, t) := x 2 = y 3 = (xy) t = 1. That is, G is (2, 3, t)generated if can be generated by just two of its elements x and y such that x is an element of order 2, y is an element of order 3 and xy has order t. In this paper, we compute (2, 3, t)-generations for the sporadic simple group O'Nan, where t is a divisor of |O'N|. For computations, we make considerable use of the computer algebra system GAP-Groups, Algorithms and Programming [20].