He attended the lectures of Carl Jacob Löwig and published his first work on stibmethyl in Schriften der Naturforschenden Gesellschaft (Writings of the Natural Science Society).

The same year he obtained the degree of Doctor of Philosophy with a thesis "Ueber die Arsenäthyle" (On ethyl compounds of arsenic) which was a notable contribution to the law of chemical valence.

Facilities for experimental research in chemistry were practically non-existent in Berlin at the time, and therefore Landolt left for Heidelberg for a newly founded institute of Robert Bunsen.

After devoting himself for a short time to the electrolytic production of calcium and lithium, Landolt started an investigation of the gases produced in the Bunsen burner, which had been constructed in the winter of 1854–55.

In 1857, he was called to Bonn where he studied the effect of the atomic composition of liquids containing carbon, hydrogen and oxygen on the transmission of light.

In 1869, he was appointed to the head of the newly founded technical college at Aachen, where a chemical institute was built according to his plans.