A methodological approach is presented for quantitative analysis of geometric parameters of nanoparticle arrays, in particular the measurement of interparticle spacings, using a Delaunay triangulation algorithm. The development is motivated by the critical role of interparticle spacings in the formation of “hot spots” in surface-enhanced Raman scattering (SERS). The algorithm for automatic identification of nanoparticle centers in microscopy images and calculation of distances between nearest neighboring particles via Delaunay triangulation is described, along with data filtering criteria and the accounting of boundary effects to improve statistical reliability. The methodology is demonstrated on self-assembled arrays of nanoparticles obtained by thermal annealing of thin Ag films. The advantages of the proposed method and its limitations are discussed. The originality of the approach and its applicability to nanometrology and morphological analysis of nanostructured surfaces are emphasized.