Tissue conditioner (temporary soft denture liner material ) could be susceptible to contact with solutions, such as denture cleanser during clinical use, continuous penetration of solution will lead to hydrolysis and dissolution of material components. The functional material could be adversely affected by this solubility. The alternative of plant extract denture cleanser containing cinnamaldehyde, such as cinnamon plant extract (Cinnamomum burmani), which has antibacterial and antimicrobial effects, is expected to have less effect on mechanical properties.The aim of this study was to determine the influence of immersion time in cinnamon extract solution on the solubility of tissue conditioner.Twenty-four cylindrical tissue conditioner samples (15 mm x 2 mm (ADA 12)), were immersed in 6 groups: groups A and B, alkaline peroxide immersion (for 7 and 14 days); groups C and D 1.5% cinnamon extract immersion (for 7 and 14 days); and groups E and F, aquadest immersion (for 7 and 14 days). The solubility of tissue conditioner material was evaluated by measuring the weight of the samples after 7 and 14 days of immersion.There was a significant difference between all groups (p<0.05). The highest average solubility of the samples was shown by groups B and D followed by groups A, C, F, and E, respectively.There was an effect of immersion time in 1,5% cinnamon extract denture cleanser on the solubility of tissue conditioner.