Quantum dynamics in reduced dimensionality using the constrained Hamiltonian method is carried out to check the (A) over tilde -> (X) over tilde relaxation via a non planar conical intersection in the vinoxy radical. This relaxation is involved in the UV photodissociation of the (B) over tilde state and in the evolution of vinoxy radical generated in the photolyse of methyl vinyl ether. Ab initio potential energy surfaces and couplings are computed at the CASSCF-level in a subspace of two active angles. An analytical diabatic model is built in order to develop the quantum dynamical treatment. The simulations emphasize the role of the initial impulsions in order to reach the non planar conical intersection from different geometries in the (A) over tilde state. (c) 2006 Elsevier B.V. All rights reserved.