He won the Nobel Prize in Chemistry in 1913 for proposing the octahedral configuration of transition metal complexes.

In 1893, Werner was the first to propose correct structures for coordination compounds containing complex ions, in which a central transition metal atom is surrounded by neutral or anionic ligands.

The three Cl− are dissociated as free ions, which Werner confirmed by measuring the conductivity of the compound in an aqueous solution, and also by chloride anion analysis using precipitation with silver nitrate.

For complexes with more than one type of ligand, Werner succeeded in explaining the number of isomers observed.

Werner proposed that these are two geometric isomers of formula [Co(NH3)4Cl2]Cl, with one Cl− ion dissociated as confirmed by conductivity measurements.

Werner also prepared complexes with optical isomers, and in 1914 he reported the first synthetic chiral compound lacking carbon, known as hexol with formula [Co(Co(NH3)4(OH)2)3]Br6.