A study was carried out to compare the effect of maturity stage and ripening chemical treatment on physico-chemical changes during post-harvest ripening and processing of tomatoes. For this purpose chemically treated and untreated tomato fruits were harvested at different maturity stage (Mature green, Breaker, Pink) and changes in different physico-chemical properties (i.e. weight loss, TSS, pH, sugar content, vitamin C content, titratable acidity) were studied at 0, 3, 6, 9 days of storage under ambient conditions. Study revealed that highest cumulative weight loss (10.25%), moisture content (94.81%), pH (4.41), and TSS/titratable acidity(16.66) were obtained from the fruits of mature green stage, while the fruits of pink stage had the highest dry matter content (13.18%), TSS(6.05 ⁰B), titratable acidity (0.445%), reducing sugar (3.97%), non-reducing sugar(1.25%), total sugar (5.21%), and vitamin C content (25.60 mg/100gm). Increase in dry matter content (from 5.22% to 11.64%), TSS (from 5.16 to 5.60), titratable acidity (from 0.308% to 0.418%), reducing sugar (from 2.28% to 3.48%) were observed during storage. A decreasing trend in moisture content (from 94.80% to 88.50%), pH (from 4.58 to 4.25), TSS/titratable acidity (from 15.54 to 13.56) and vitamin C content (from 17.94mg/100g to 13.68 mg/100 g) was observed during storage. Untreated tomato (5.33) had higher TSS than treated (5.23) one. Reducing sugar was higher in untreated tomato (2.49%) than that of treated tomato (2.36%). Non-reducing sugar content was higher in untreated (0.901%) than treated tomato (0.886%). Vitamin C content was higher in untreated (17.94 mg/100g) tomato than the treated tomatoes (17.73mg/100g). Moisture content was higher in untreated tomatoes (94.09%) than that of treated tomatoes (93.96%) and dry matter content of untreated tomatoes (6.01%) was higher than that of treated tomatoes (5.84%).The study suggested that tomato fruits harvested at breaker stage may be suitable for fresh consumption and for long distance transportation.