Annealing in a hydrogen atmosphere of silicate glass plates doped by Ag+ ions leads to the reduction of silver to a metallic state (Ag0) and to the formation of silver nanoclusters. The kinetics of clustering during hydrogen diffusion into the glass and diffusion of Ag0 atoms in the glass matrix have been studied in a temperature ranging from 160 to 200oC by SEM, AFM and optical spectrometry. The absorption spectra have a peak near 410 nm corresponding to the surface plasmon resonance in Ag clusters. The position of the peak moves as the clusters grow. A theoretical analysis of the absorption spectra allowed us to estimate the cluster size as a function of time, as well as the thickness of the layer filled by clusters, which also changes with time. From AFM data we could measure the kinetics of cluster growth on the surface. We have theoretically analyzed the kinetics of cluster growth during reactive hydrogen diffusion, the kinetics of bulk cluster growth, surface cluster growth, and thickening of the layer filled by clusters.