In this study, the process of n-hexane spray formation was investigated under a wide range of environmental conditions. The main aim of this research was to determine whether the global and visual properties of n-hexane spray change when the back pressure exceeds the critical pressure of the injected liquid. For this purpose, the liquid length and the boundary profile between the spray and surrounding air obtained by high-speed imaging of the Mie scattering signal were used. A major advantage of this work is that besides measuring global spray parameters, it provides quantitative analysis of the visual properties of the spray images; thus, the image analysis is not limited to qualitative visual impression. The results obtained in this study showed no step change in liquid length in terms of exceeding the critical parameters. Although qualitatively the boundary between the injected liquid and the surrounding gas seemed to become smoother in high-pressure and high-temperature conditions, the qualitative analysis did not support this observation. Graphic abstract Open image in new window