The Molecular Tagging (MT) technique emerges as a promising tool for local velocity and temperature field measurements of rarefied gas flows [1, 2]. Recently, Molecular Tagging Velocimetry (MTV) has been successfully implemented to measure velocity profiles of gas flows within a rectangular mini-channels both in the continuum regime at relatively high pressure and early slip-flow regime at lower pressure [3-6]. Due to diffusion effects, it is not possible to accurately measure velocity profiles by only dividing the displacement profile of the tagged line by time of flight. To overcome this challenge, a reconstruction method considering Taylor dispersion was developed to extract the velocity profile, while taking into account the diffusion effects of the tracer molecules within the carrier gas [7]. This reconstruction method successfully obtained the correct velocity profile of continuum flow [3, 5]. Nonetheless, the method still encounters difficulties when applied to slip-flow regime due to more pronounced diffusion effects. Since there is currently large uncertainty of the kinetic diameter value of acetone vapor in the literature [7-11], the diffusion coefficient value is uncertain especially at low pressures. For this reason, we propose an original optical method to measure the diffusion coefficient of acetone vapor for a wide range of pressures at temperatures higher than the ambient temperature. To the best of our knowledge, this study marks the first measurements of self-diffusion coefficients for gaseous acetone at different temperatures utilizing this technique.