The research was aimed to examine the effect of different concentration of KNO3 and fruit maturitylevel on the seed viability of papaya. This research used Completely Randomized Design (CRD)factorial with two main treatments. The first treatment was fruit maturity level (A0 : 75% dan A1 :100%). The second treatment was concentration of KNO3 (B1 = 0 M ; B2 = 0,05 M ; B3 = 0,1 M ; B4 =0,15 M ; B5 = 0,2 M). Seedling parameters observed were germination rate, seed growth rate, vigourindex, and maximum growth potential. Nursery parameters observed were plant height and leaf area.Data were analyzed with Analysis of Variance (ANOVA) followed by Duncan Multiple Range Test(DMRT) at 5%. The interaction between fruit maturity and KNO3 concentration showed significantly ingermination rate, seed growth rate, vigour index, maximum growth potential and plant height. Leafarea were only affected by KNO3 concentration. This showed that fruit maturity level and KNO3concentration were significantly affects seed viability.