He is a former member (1990) and chairman (2000) of the NASA Astronomy and Astrophysics Survey Committee (the "decadal review") and former director of the Space Sciences Laboratory (SSL) at UCB.
McKee performed the first simulations of relativistic counter-streaming plasmas as part of his Ph.D. thesis at Berkeley (1970).
Since joining the Physics and Astronomy Departments in Berkeley in 1974, he has devoted much of his research to studying processes in the interstellar medium, including evaporation of clouds, the structure of shock waves in atomic and molecular gas, and the dynamics of blast waves in both homogeneous and inhomogeneous media.
In collaboration with Jeremiah Ostriker (Columbia University), he developed the three-phase model of the interstellar medium, which has been widely used to organize and interpret observational data.
His research on quasars has included development of the relativistic blast wave model for variability, introduction of reverberation mapping to analyze variable emission line profiles, the two-phase model for quasar emission line regions, and the development of the theory of coronae and winds from accretion disks.