ABSTRACT Ellen Gleditsch (1879-1968) became Norway's first authority of radioactivity and the country's second female professor. After several years in international centers of radiochemistry, Gleditsch returned to Norway, becoming associate professor and later full professor of chemistry. Between 1916 and 1946 Gleditsch tried to establish a laboratory of radiochemistry at the University of Oslo, a career which included network building, grant applications, travels abroad, committee work, research, teaching, supervision, popularization, and war resistance work. Establishing a new field was demanding; only under her student, Alexis Pappas, was her field institutionalized at Oslo. This paper presents Gleditsch's everyday life at the Chemistry Department, with emphasis on her formation of a research and teaching laboratory of radiochemistry. Her main scientific work during this period is presented and discussed, including atomic weight determination of chlorine, age calculations in minerals, the hunt for actinium's ancestor and investigations on 40 K.