Emeritus Professor deLeon specialized in policy research on issues of technology development, assessment, and utilization, with substantive expertise on national security and energy. On seven occasions, he has been named his School's outstanding research scholar. In AY 2001/02, he received his School's Outstanding Service Award, and in 2002/03, its Outstanding Teacher Award. In 2011, the University of Colorado Regents named him a Distinguished Professor, the highest honor for the university's faculty.
In August 2000, he was awarded the prestigious (and unsolicited) Harold D. Lasswell Award by the Policy Studies Organization as "an outstanding scholar in contributing to our understanding of the substance and process of public policy."