Under what conditions is G for a reaction always positive-apex?

The Gibbs free energy change (ΔG) for a reaction is always positive when the reaction is non-spontaneous under the given conditions. This typically occurs at high temperatures for endothermic reactions (where ΔH is positive and ΔS is negative), or when both ΔH is positive and the entropy change (ΔS) is negative. In these cases, the term TΔS is either small or negative, resulting in ΔG being greater than zero.