Implementing a new scheduler within a real-time operating system is challenging. The transition from a theoretical scheduling policy specification to a real platform implementation requires several constraints to be taken into account. Therefore, a verification process must support the implementation work to give it a level of confidence and validate its correctness. In this paper, we present such a verification approach which is based on model-checking. It aims to identify subtle issues in our implementation of scheduling policies within an OSEK/VDX real-time operating system called Trampoline. As an example, the approach is conducted on elaborated models of an implemented G-EDF scheduler along with other OS components that contribute to the scheduling decision. Then, the verification is carried out by checking a set of relevant requirements which are identified based on the expected behavior of the scheduler as specified in the literature. This approach demonstrated its feasibility since potential issues are detected in our implementation. CCS CONCEPTS • Computer systems organization → Real-time operating systems ; • Theory of computation → Verification by model checking.