In this article, we study the enumeration by length of several walk models on the square lattice. We obtain bijections between walks in the upper half-plane returning to the x-axis and walks in the quarter plane. A recent work by Bostan, Chyzak, and Mahboubi has given a bijection for models using small north, west, and south-east steps. We adapt and generalize it to a bijection between half-plane walks using those three steps in two colours and a quarterplane model over the symmetrized step set consisting of north, north-west, west, south, south-east, and east. We then generalize our bijections to certain models with large steps: for given p ≥ 1, a bijection is given between the half-plane and quarter-plane models obtained by keeping the small south-east step and replacing the two steps north and west of length 1 by the p + 1 steps of length p in directions between north and west. This model is close to, but distinct from, the model of generalized tandem walks studied by Bousquet-Mélou, Fusy, and Raschel.1 In the absence of a written text yet, one can consult [7] for an earlier, related presentation. 2 The original presentation in [3] uses automata with infinitely many states and no auxiliary memory, but, in view of the generalization to come, we prefer an equivalent presentation with finitely many states and counters that encode the numbering of the states considered in [3].-Tandem words are classically those words on S 1 giving rise to a walk in the quarter plane. We will also call them quarter-plane 1-tandem words:-By relaxing the quarter-plane constraint, but forcing the final height, we obtain what we will call half-plane 1-tandem words:The bijection M H is obvious.• {1, 2, 3}. We restrict the classical class of Yamanouchi words (using any letters from N * ) to those words using only the first three integers:Y 3 = {w ∈ {1, 2, 3} * : ∀w , w ≤ w ⇒ |w | 1 ≥ |w | 2 ≥ |w | 3 }.The bijection Y 3 Q is obvious.