The Se90Te10 alloy readily forms a stable chalcogenide glass that has widely documented applications. In this work, the nucleation behavior of Se90Te10 was studied by infrared microscopy as well as by differential scanning calorimetry. Nuclei densities were directly estimated by image analysis of micrographs of samples following nucleation-development heat treatments, and they were subsequently compared with indirect quantitative estimation by DSC. Both the methods yielded comparable results in the non-intersecting region of the nucleation-growth curves while diverging in the nucleation-growth domain. The rates of nucleation could be adequately described by the classical nucleation theory.