George Kalmus has made a number of important contributions to particle physics, which include exploiting the bubble chamber technique to make significant contributions to the physics of strong and weak interactions. Notable work in which George played a leading role include: the first quantitative study of Ke₄ decay with an analysis of low energy pi–pi interaction; studies of baryon resonances both strange and non-strange; and the first observation of direct electron production in hadron collisions.

The last had implications for charmed particle production. George went on to study photoproduction of charmed particles, and is an expert on the production and decay of these short-lived particles. George, with his group, played a leading role in the design, realisation and analysis of the DELPHI experiment at the LEP collider at CERN. He then went on to study the ultra-rare decay modes of the K-short meson at CERN. George was Director of Particle Physics at the Rutherford Appleton Lab from 1986 to 1997 and Chairman of the CERN Scientific Policy Committee from 1999 to 2001.