[4] After high school she initially planned to become a painter due the influence of Käthe Kollwitz but her father was against it and persuaded her to become a chemist instead.

On 7 Septmenber 1930, she was fined 30 Reichsmarks for distributing "communist leaflets" in Esslingen[3] during International Youth Camp, after refusing to hand them to the police.

[3] In Berlin, she became actively involved in volunteering with the KPD and began her political education by attending classes at the Marxist Workers' School.

[3] It was assumed her friend Walter Ehlen was the father[3] or possibly Fritz Rau, who died in the same month, while in Gestapo custody[2] in Moabit prison.

[9] or Württemberg KPD district leader Stefan Lovász [de][10] (sources vary) In September of the same year, she moved back to Stuttgart to be with her family and found work as a stenotypist at her father's engineering office.

[3] Herrmann worked together with Diethelm Scheer [de] for the KPD's intelligence unit, which collected evidence of Nazi Germany's illegal German re-armament programme.

[11] Working with a boat builder and KPD official Josef Steidle [de] and the locksmith Artur Görlitz, she obtained information about re-armament, concerning secret weapons projects — munitions production at the Dornier aircraft factory in Friedrichshafen and the building of an underground ammunition factory (Muna) near Celle, via Eugen Beck, who was employeed by the Stehle company in Stuttgart.

During the search, the Gestapo found a copy of the plan for the ammunition plant hidden behind a mirror, along with KPD and Marxist literature.

[16] The bodies of the five people were not buried, instead were given to anatomy professor Hermann Stieve of Charité Anatomical Institute for medical research.

[3][17] In East Germany, many schools, streets, and institutions were named after her, including in Berlin, Neubrandenburg, Erfurt, Gera, Jena, Weimar and Chemnitz.

A commission was formed to examine the proposal who recommended that "the memory of Lilo Herrmann be maintained and promoted, but to refrain from building a monument only intended for it".