The viability kernel corresponds to the set of all state vectors of a controlled dynamic system that are viable, i.e., such that there exists an input such that the system will not enter inside a forbidden zone. In this paper, we propose a method which computes an inner and an outer approximation of the viability kernel in a guaranteed way. Our method is based on interval analysis and uses the notions of V-viability and capture basin. We illustrate our approach on the car on the hill problem. A software package has been developed to solve any 2D-problem.