A test case has been defined to investigate experimentally and by numerical simulation the transient ignition phenomenology when igniting coaxial injected O2 and H2 by a laser. Using high-speed photography the temporal evolution of the flame and its anchoring at the injector could be visualized. From the analysis of the flame front movement flame velocities and convection velocities have been determined at specific phases during the ignition transient. 3D simulation were undertaken but not yet achieved., A first step using 2D axisymmetrical model allow to adjust grid, laser ignition modelization and to performe some parameter studies, Ignition was not reached in this configuration but preliminary results are encouraging. Finally, application to the VINCI was described where ignition uses a torch.