Volume 4 of Atomic and Plasma–Material Interaction Data for Fusion contains the result of a critical data evaluation of the cross-sections of ground state and excited hydrogen atoms colliding with the basic fusion plasma constituents, the electrons and protons, and with the multiply charged ions of major plasma impurities. The primary purpose of the present volume is to provide a complete set of the collisional data required for the modelling of neutral hydrogen beam penetration in a thermonuclear fusion plasma.