Let G be a group. An element g ∈ G is called reversible if it is conjugate to g −1 within G, and called strongly reversible if it is conjugate to g −1 by an order two element of G. Let H n H be the n-dimensional quaternionic hyperbolic space. Let PSp(n, 1) be the isometry group of H n H . In this paper, we classify reversible and strongly reversible elements in Sp(n) and Sp(n, 1). Also, we prove that all the elements of PSp(n, 1) are strongly reversible.