The aim of study was to determine the percentage of acid and its influence on characteristic effervescent tablet of tamarillo. The percentages of acid addition that consist with citric acid and tartaric acid (1:1) were 15%, 20%, 25%, 30% and 35%. Water content, pH solution, vitamin C content, soluble duration, friability of tablet and organoleptic test on colour, aroma and flavour of tamarillo effervescent tablet were determined after addition of acid. The results showed that the difference in percentage of acid addition significantly affected to the water content, pH solution, soluble duration and friability of tablets. Based on organoleptic test, the tablet consist of 25% addition of acid was the best percentage of acid addition. The quality parameters in this percentage were the water content 6.09%, pH solution 4.80, vitamin C 498.0800 mg/tablet, soluble duration 3.96 minute, friability of tablet 0.11%, while the averages of organoleptic test for colour were 3.40 (ordinary), aroma 3.36 (ordinary), and flavour 3.76 (like).