In this paper, we investigate the Dirichlet-to-Neumann operator associated with second order quasi-linear operators of p-Laplace type for 1 < p < ∞, which acts on the boundary of a bounded Lipschitz domain in R d for d ≥ 2. We establish well-posedness and Hölder-continuity with uniform estimates of weak solutions of some elliptic boundary-value problems involving the Dirichlet-to-Neumann operator. By employing these regularity results of weak solutions of elliptic problems, we show that the semigroup generated by the negative Dirichlet-to-Neumann operator on L q enjoys an L q − C 0,α -smoothing effect and the negative Dirichlet-to-Neumann operator on the set of continuous functions on the boundary of the domain generates a strongly continuous and order-preserving semigroup. Moreover, we establish convergence in large time with decay rates of all trajectories of the semigroup, and in the singular case (1 + ε) ∨ 2d d+2 ≤ p < 2 for some ε > 0, we give upper estimates of the finite time of extinction.