Grazing incidence X-ray photoemission spectroscopy (GIXPS) can be used to obtain both chemical and structural information to describe the depth profile for a given ultrathin film. This work describes the use of GIXPS to characterize the thickness of a silicon oxynitride ultrathin films grown on a silicon substrate. GIXPS utilizes the inherent optical and material properties of the film, along with the angle of the incident X-rays with respect to the sample surface to control the electric field penetration into the sample. By adjusting the angle of incident X-rays from zero to some value slightly greater than the angle for total X-ray external reflection, it is possible to nondestructively probe the nature of the film depth profile. The resulting angle dependent photoemission spectrum contains information that describes the physical properties of the sample, including density and thickness. Thickness measurements made using GIXPS will be compared to those acquired using other analytical techniques from the same group of samples.