This work is devoted to the analysis of a fully-implicit numerical scheme for the critical generalized Korteweg-de Vries equation (GKdV with p = 4) in a bounded domain with a localized damping term. The damping is supported in a subset of the domain, so that the solutions of the continuous model issuing from small data are globally defined and exponentially decreasing in the energy space. Based in this asymptotic behavior of the solution, we introduce a finite difference scheme, which despite being one of the first order, has the good property to converge in L 4 -strong. Combining this strong convergence with discrete multipliers and a contradiction argument, we show that the smallness of the initial condition leads to the uniform (with This work was supported by grant 49.0987/2005-2 of the Cooperation CNPq/CONICYT (Brasil-Chile). M.S. has been also supported by Fondecyt Project #1070694, FONDAP and BASAL projects CMM, Universidad de Chile, and CI 2 MA, Universidad de Concepción. O.V.V. has been supported by Postdoctoral fellowship of LNCC (National Laboratory for Scientific Computation), and he is grateful for the dependences of the LNCC while he realized postdoctorate.