ABSTRACT The experiment was conducted to study the effect of interaction between the types of organic solvent and soaking duration to expired watermelon seed viability, and to determine the effect of each of these factors. This research was conducted in the Laboratory of Seed Science and Technology, Faculty of Agriculture, Syiah Kuala University, Darussalam, Banda Aceh, which lasted from February to April 2013. This research used Factorial Completely Randomized Design with three replications. The first factor was kinds of organic solvent solution which consist of avocado, mango, and tea solution. The second factor was the duration of seed immersion to the solutions, which consists of 2, 4, and 6 hours. The results showed that there is no significant interaction between the types of organic solvent and immersion duration on the observed parameters. Types of organic solvents effect very significant on the potential for growth and the effect was not significantly on germination, growth speed, simultaneity grows, total germination and normal seedling dry weight. Best type of organic solvent solution is avocado’s. Immersion time significantly affect normal seedling dry weight and not significantly effect on the value of potential growth, germination, growth speed, simultaneity grow, and time required to achieve 50% total germination. Soaking duration, best observed is 6 hours. Keywords: Immersion duration, organic solvent, watermelon seed, expired seed, Citrullus vulgaris