Abstract Let f be a polynomial with coefficients in the ring OS {O_{S}} of S -integers of a number field K , b a non-zero S -integer, and m an integer ≥2 {\geq 2} . We consider the following equation (⋆) {(\star)} : f(x)=bym {f(x)=by^{m}} in x,y∈OS {x,y\in O_{S}} . Under the well-known LeVeque condition, we give fully explicit upper bounds in terms of K,S,f,m {K,S,f,m} and the S -norm of b for the heights of the solutions x of equation (⋆) {(\star)} . Further, we give an explicit bound C in terms of K,S,f {K,S,f} and the S -norm of b such that if m>C {m>C} equation (⋆) {(\star)} has only solutions with y=0 {y=0} or a root of unity. Our results are more detailed versions of work of Treli