Acidulants are an important functional ingredient group in the food industry, providing sourness, lowering pH, ensuring safe processing, and extending shelf life. Hence, understanding the effect of acids on sensory characteristics of foods is critical. Of the many topics dealing with acidulants, sourness is a topic where considerable research has been done. To a lesser extent researchers have examined how acidulants, and sourness generated from the hydrogen ion or the acid anion, effect the perception of fruit flavor. A series of experiments was conducted to determine how selected acid types, pH, and sourness effect the perception of selected fruit flavors in model systems. First, selected organic acids (citric, lactic, malic) were evaluated on an equivalent weight (0.4%w/v) at 5 fixed pH levels (2.6, 3.0, 3.4, 3.8, and 4.2), in a solution of water, sugar (10% w/v), and fruit flavor (lemon, and strawberry) to determine if acid type and pH level effect fruit flavor perception. Generalized descriptive analysis was used to characterize the differences between the treatments for the descriptors of fruit flavor, sweetness, sourness, and astringency. The pH influenced fruit flavor intensity more than acid. Lemon flavor increased with decreasing pH, while strawberry flavor decreased with increasing pH. These findings suggest that pH effects the perception of fruit flavor differently depending on the system. The results described for the lemon and strawberry flavored experiments are part of a larger study involving phosphoric acid and blends of citric, lactic, and malic acid- each paired in equal proportions-in apple, forest berry, orange and tropical flavored systems. In the second, three equi-sourness levels of selected acids (citric, lactic, malic) were generated at pH 3.0, in a solution of water, sugar (10% w/v), and selected fruit flavor (lemon, strawberry) to determine if sourness from selected acidulants effect fruit flavor perception differently. Increasing sourness intensity increased lemon and strawberry flavor. In the strawberry experiment malic acid provided more strawberry flavor than citric and lactic acid at the low sourness level only. These findings suggest that sourness effects flavor more than acid type.