Absorption kinetics and first-order reaction models on fractal lattices are studied. Adsorption kinetics in macro/microporous fractal solids showing fractal scaling properties and a complex topological pore-network structure are developed by considering the coupling of two fractal graphs. For first-order reactions on fractal substrata, the exact determination of the behavior of the effectiveness factor vs the Thiele modulus is obtained. A model for analyzing the spatial concentration distribution in a fractal catalyst is proposed.