Verification of real-time application schedulability is usually performed using a very abstract representation of the system which poorly supports inter-task dependencies. This paper presents the use of model-checking techniques to check the schedulability on a detailed model of a multi-core operating system. The operating system as a whole is modeled by a High-level Petri net reproducing the control flow and using the same variables as those of the implementation. Each task of the application is represented by a Stopwatch Petri Net whose transitions carry Best-Case Execution Time and Worst-Case Execution Time [BCET ,W CET ] firing intervals and make service calls to the OS. Preemption is supported by means of stopwatches. Verification is performed using observers and allows to determine the schedulability of the multi-core application, or, using parameters on the firing intervals, allows determining under which temporal conditions the application is schedulable. CCS CONCEPTS • Software and its engineering → Formal software verification; • Computer systems organization → Real-time operating systems; • Theory of computation → Verification by model checking.