  We prove an existence and uniqueness result for quasilinear Stochastic PDEs
with obstacle (OSPDE in short). Our method is based on analytical technics
coming from the parabolic potential theory. The solution is expressed as a pair
$(u,\nu)$ where $u$ is a predictable continuous process which takes values in a
proper Sobolev space and $\nu$ is a random regular measure satisfying the
minimal Skohorod condition.
