He was born in Vienna. He has been professor at the Geologischen Institut of the University of Vienna since 1969. 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).
Later in his life, he turned to esoteric fields and published obscure hypotheses for which he was strongly criticized by the scientific community. In 1993, with his wife Edith, 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. See Tollmann's hypothetical bolide. In 1998 the husband-and-wife team published Das Weltenjahr geht zur Neige: Mythos und Wahrheit der Prophezeiungen. The book was on the Austrian bestseller list for weeks. In August 1999, he predicted a world-wide catastrophy that he awaited in his bunker in Lower Austria. In December 2003, Tollmann published Und die Wahrheit siegt schließlich doch (And the truth finally prevails).