He was a political activist working to free Austria from nuclear energy and a founder of the Austrian Green Party (Vereinten Grünen Österreichs or VGÖ).
In 1993, with his wife, paleontologist Edith Kristan-Tollmann, he published a monograph, Und die Sintflut gab es doch.
Vom Mythos zur historischen Wahrheit, which claimed that Noah's flood was the consequence of a bolide impact about 9500 years ago, and supported the claim through geology (impact craters, iridium, shatter cones, stress lamination of minerals, radiocarbon dating, dendrochronology, a peak of acid in the Greenland ice) and legends and folk traditions.
In 1998 the husband-and-wife team (posthumously; his wife had died in 1995) published Das Weltenjahr geht zur Neige: Mythos und Wahrheit der Prophezeiungen.
[2] In December 2003, Tollmann published Und die Wahrheit siegt schließlich doch (And the truth finally prevails).