In this paper, we give the first description of the collision of two solitons for a nonintegrable equation in a special regime. We consider solutions of the quartic gKdV equation ∂tu + ∂x(∂ 2 x u + u 4 ) = 0, which behave aswhere Qc(x − ct) is a soliton and η(t) H 1 Qc 2 H 1 Qc 1 H 1 . The global behavior of u(t) is given by the following stability result: for all t ∈ R, u(t, x) = Q c 1 (t) (x − y1(t)) + Q c 2 (t) (x − y2(t)) + η(t, x), where η(t) H 1 Qc 2 H 1 and limt→+∞ c1(t) = c