Mask pattern transferred transient grating, which is a convenient new technique in the class of optical heterodyne detected transient grating, is applied to photochromic molecule (spiropyran) in 2-propanol solution. The spatial modulations of optical properties of the material is generated by transferring an ultra-violet light pattern directly from a metal film grating into the sample solution and detected through the diffraction of a probe beam. The thermal conductivity of the solvent and the diffusion coefficients of the solute molecules were obtained and compared with the calculated values. This method has many advantages compared to the conventional techniques. (c) 2005 Elsevier B.V. All rights reserved.