Abstract. Nearinfrared (NIR) spectroscopy technique shave shown promise as rapid and nondestructive tools to evaluate the various internal quality attributes of fruits. In mango fruits cv Gedong Gincu, acidity (pH) is one of the main quality attribute. Prediction of acidity in mango fruits is generaly carried out destructively. The objective of this study was to develop calibration model and prediction of pH in mango fruit cv. Gedong Gincu using NIR spectroscopy. The transmission spectra of mango fruits were obtained in the wave length range from 1000 to 2400 nm.The prediction model was developed by partial least square(PLS) regression. The coefficient of corrrelation (r) of pH was 0.9042 and the standard error of prediction (SEP) was 0.12, respectively. It is concluded that by using the NIR measurement system, in the appropriate spectral range, it is possible to nondestructively predict the pH of mango fruit.