We consider a long-range scattering theory for discrete Schrödinger operators on the hexagonal lattice, which describe tight-binding Hamiltonians on the graphene sheet. We construct Isozaki-Kitada modifiers for a pair of the difference Laplacian on the hexagonal lattice and perturbed operators with long-range potentials. We prove that these modified wave operators exist and that they are asymptotically complete.Date: December 21, 2018.We give notations for the description of the main theorem. For a selfadjoint operator S and an Borel set I ⊂ R, E S (I) denotes the spectral projection of S onto I and H ac (S) denotes the absolutely continuous subspace of S. The main theorem of this paper is the following. Theorem 1.3. Assume that V satisfies Assumption 1.1. Then for any open set Γ ⋐ [−3, 3]\{0, ±1, ±3}, one can construct a Fredholm operator J on H such that there exist modified wave operators W ± J (Γ) := s-lim t→±∞ e itH Je −itH 0 E H 0 (Γ) (1.3) and the following properties hold: i)Intertwining property HW ± J (Γ) = W ± J (Γ)H 0 . ii)Partial isometries W ± J (Γ)u = E H 0 (Γ)u . iii)Asymptotic completeness Ran W ± J (Γ) = E H (Γ)H ac (H).