This article reports on a new apparatus, called the laser double ablation reactor, for studies on the reactivity of clusters. Structure and operative principle of the apparatus were presented. With this apparatus reactions between manganese/carbon clusters and sulfur clusters, and between silver and sulfur clusters were studied. The experiments indicate that manganese/carbon clusters appear inert when they react with sulfur clusters, while for reactions between silver and sulfur clusters, the products[AgS4]+,[AgS8]+,[AgS12]+,and[AgS16]+,mainly are obtained. In comparison to the results obtained by Fourier transform ion cyclotron resonance, it shows that the new apparatus is very efficient for study on reactions between clusters. ©1998 American Institute of Physics.