<p>We present here an experimental study where the instability and dewetting of thin polystyrene films on glass substrates is examined by immersing it in two different types of dewetting media, a binary, water-methyl ethyl ketone (MEK) and a ternary (water-acetone-MEK) mixtures of solvent and non-solvent(s). With this we have established a direct link between the miscibility of solvents and its efficacy as a dewetting media. The dewetting kinetics, droplet diameter (<i>d</i>), and the average distance between droplets (<i>λ</i>) of dewetted structures were all significantly affected by the type of dewetting media and the volume fraction of solvent in it. The length scales (<i>λ</i> and <i>d</i>) were found to increase in the binary mixture as the solvent fraction is decreased, whereas lengthscales of dewetting have decreased in the ternary mixture as the solvent fraction is decreased. <i>d</i> and <i>λ</i> in the two types of dewetting media differed significantly when the solvent fraction in the binary mixture was close to the solubility limit of MEK in water, but this difference diminished as the concentration of the solvent in the mixture was decreased. <i>d</i> and <i>λ</i> both increased with the increased film thickness, but the thickness dependency of <i>λ</i> was significantly weaker than the spinodal dewetting (<i>λ</i> ~ <i>h</i>²) suggesting it to be primarily defect-induced dewetting. This clearly demonstrates that the miscibility of the solvent and water has a substantial impact on the dewetting mixture’s effectiveness, subsequently impacting the dewetting kinetics.</p>