We shall consider the following semi-linear problem with a Neumann boundary conditionwhere B 1 is the unit ball in R N , N ≥ 2, a, b are nonnegative radial functions, and p, q are distinct numbers greater than or equal to 2. We shall assume no growth condition on p and q. Our plan is to use a new variational principle that allows one to deal with problems with supercritical Sobolev non-linearities. Indeed, we first find a critical point of the Euler-Lagrange functional associated with this equation over a suitable closed and convex set. Then we shall use this new variational principle to deduce that the restricted critical point of the Euler-Lagrange functional is an actual critical point. Keywords Semi-linear elliptic problems • Calculus of variations • Variational principles Mathematics Subject Classification 35J15 • 58E30 Abbas Moameni is pleased to acknowledge the support of the National Sciences and Engineering Research Council of Canada. Leila Salimi is supported by a Grant from IPM (No. 96470045).