For each Artin group, the reduced $\eltwo$-cohomology of (the universal cover of) its ‘Salvetti complex’ is computed. This is a CW-complex which is conjectured to be a model for the classifying space of the Artin group. In the many cases when this conjecture is known to hold the calculation describes the reduced $\eltwo$-cohomology of the Artin group.