Following [14] and [12], we formalize the notion of an oscillatory integral interpreted as a functional on the amplitudes supported near a fixed critical point x 0 of the phase function with zero critical value. We relate to an oscillatory integral two objects, a formal oscillatory integral kernel and the full formal asymptotic expansion at x 0 . The formal asymptotic expansion is a formal distribution supported at x 0 which is applied to the amplitude. In [12] this distribution itself is called a formal oscillatory integral (FOI). We establish a correspondence between the formal oscillatory integral kernels and the FOIs based upon a number of axiomatic properties of a FOI expressed in terms of its formal integral kernel. Then we consider a family of polydifferential operators related to a star product with separation of variables on a pseudo-Kähler manifold. These operators evaluated at a point are FOIs. We completely identify their formal oscillatory kernels.2010 Mathematics Subject Classification. 53D55, 81Q20. Key words and phrases. deformation quantization, oscillatory integral, stationary phase. 1 2. Formal oscillatory integrals Given a vector space V , denote by V ((ν)) the space of formal vectorswhere k ∈ Z and v r ∈ V for r ≥ k. Let M be an oriented manifold 1 of dimension n and let x 0 be a fixed point in M. Consider a complex 1 We require throughout the paper that the manifold M be oriented in order to deal with volume forms instead of densities.