Magnitude estimates for perceived intensity and pleasantness of suprathreshold concentrations of citric acid in solution and drink were examined in 180 healthy, free-living subjects divided into three groups: young (20-29 years), old (70-79 years) and very old (80-99 years). Psychophysical functions showed significant age effects. For both aqueous and food systems, the old gave higher intensity estimates to high acid concentrations and lower intensity estimates to low acid levels compared to the young and very old whose estimates were comparable. Sex had a significant effect on the intensity estimates with the women giving low acid levels lower estimates and high acid levels higher estimates than the men. All subjects gave low acid levels in solution lower intensity estimates than comparable drinks while at high concentrations, higher intensity estimates were given to solutions than drinks. Trend analysis of pleasantness estimates indicated significant age group differences. For both systems, the breakpoint, the acid level assigned the highest pleasantness estimate was lower for the young than for the elderly.