After being awarded her doctorate in 1906, Lise Meitner's first job was in the institute of her former professor, Ludwig Boltzman. Despite her good relationship with Boltzman, she realised that the only possible jobs available in Vienna for a woman in her field were either teaching or tutoring, neither of which appealed to her. So in 1907, despite her parents' objections to 'young women travelling alone', Meitner left Vienna for Belin, where she hoped to attend the lectures of Max Planck. Her parents, despite their objections to travel, funded her studies with a generous allowance.

At the University of Berlin, Meitner began her studies in the new and exciting field of radioactivity. It was at this time that she met her collaborator, the gifted organic chemist, Otto Hahn, and they began a long professional association. Ironically, the room they used for their experiments was contaminated with mercury, which caused them both to suffer from headaches. This, and the excessive radiation in such a small space, was highly unsatisfactory.

Then in 1913, she moved from the university to the newly formed Kaiser Wilhelm Institute, where the two commenced research on the emission of beta radiation from radioactive elements. This was the same institute that originally forbade Meitner to work in the main laboratory.

As their experience progressed, Meitner and Hahn began research into the elemental transformations at the high end of the periodic table. After the outbreak of WWI, Meitner began to a search for the 'parent' element of actinium. Their work was interrupted when Lise Meitner volunteered to work as a radiologist in an Austrian field hospital as part of the war effort. In France, Meitner's hero, Marie Curie, was undertaking similar work for her country.

Despite the war and her medical work, Meitner and Hahn were able to meet regularly and continue some work. After Meitner left the war service, she and Hahn announced the discovery of Protactinium, the parent element of Actinium, in 1917. In 1918, she was appointed as head of the Physics department of the Kaiser Wilhelm Institute, where she worked until 1926, when she was appointed as a professor of Physics at the University of Berlin.