His shop became the second-largest apothecary in Berlin, and the most productive artisanal chemical research center in Europe.

[2] Klaproth was a major systematizer of analytical chemistry,[3] and an independent inventor of gravimetric analysis.

[1] An exact and conscientious worker, Klaproth did much to improve and systematise the processes of analytical chemistry and mineralogy.

His appreciation of the value of quantitative methods led him to become one of the earliest adherents of the Lavoisierian doctrines outside France.

[8] Klaproth independently discovered cerium (1803), a rare earth element, around the same time as Jöns Jacob Berzelius and Wilhelm Hisinger, in the winter of 1803.

[18] Klaproth clarified the composition of numerous substances until then imperfectly known, including compounds of then newly recognised elements tellurium, strontium and chromium.

[8][19][20][2] The existence of tellurium was first suggested in 1783 by Franz-Joseph Mueller von Reichenstein, an Austrian mining engineer who was examining Transylvanian gold samples.

He credited Mueller as its discoverer, and suggested that the heavy metal be named "tellus", Latin for 'earth'.

[26] Klaproth, Thomas Charles Hope, and Richard Kirwan independently studied and reported on the properties of strontianite, the preparation of compounds of strontium, and their differentiation from those of barium.

[27][28] Louis Nicolas Vauquelin reported the existence of a new element common to emerald and beryl in 1798, and suggested that it be named "glucine".

Klaproth confirmed the presence of a new element, and became involved in a lengthy and ongoing debate over its name by suggesting "beryllia".

[23][8][16]: 348–352 [24][29] Klaproth published extensively, collecting over 200 papers by himself in Beiträge zur chemischen Kenntnis der Mineralkörper (5 vols., 1795–1810) and Chemische Abhandlungen gemischten Inhalts (1815).

[31] In 1823, botanist Carl Sigismund Kunth published a genus of flowering plants (belonging to the family Loasaceae), from Central America as Klaprothia in his honour.