We show that the Reeb vector field of an almost cosymplectic three-manifold is minimal if and only if it is an eigenvector of the Ricci operator. Then, we show that Reeb vector field x of an almost cosymplectic three-manifold M is minimal if and only if M is šk, m, nŽ-space on an open dense subset. After, using the notion of strongly normal unit vector field introduced in [8], we study the minimality of x for an almost cosymplectic š2n ž 1Ž-manifold. Finally, we classify a special class of almost cosymplectic three-manifold whose Reeb vector field is minimal.