John Eland is renowned for his conceptual, instrumental and methodological contributions to the study of molecular ionisation by photon and electron impact. His outstanding work in photoelectron spectroscopy supported subsequent applications in ion spectroscopy and analysis, and were cogently presented in his influential book. He is particularly well regarded for his development and use of coincidence techniques for studying molecular ionisation, subsequent dynamic relaxation processes — photon emission, fragmentation (including ion pair formation) — and momentum correlations; his work on multiple ionisation and the dynamics of the ensuing dissociation processes has been especially important and influential. His current work is concentrated on ionisation of inner shell electrons and the ensuing relaxation processes.