Quantum wave packet approach to the Eley-Rideal reactive scattering between a gas phase atom and an adsorbate. A quantum wave packet code for studying Eley-Rideal scattering reactions of gas phase atoms with atoms adsorbed onto a rigid substrate is described. The flat surface approximation reduces the full treatment to three-dimensional (3D) numerical resolutions. The time evolution relies on the split operator propagator in a discrete, cylindrical coordinate representation. A pseudospectral strategy is used to evaluate efficiently the Hamiltonian operation by means of sequential 1D transformations between coordinate and momentum spaces. Fast Fourier transforms are performed for the two Cartesian coordinates whereas a discrete Bessel transform is applied for the cylindrical radius. The potential energy representation is based on the so-called LEPS model. Flux analysis in the product molecular region yields energy-resolved reaction cross sections and rovibrational distributions.