The influence of the pH of precipitation on the morphology and the nitrate retention of aluminas prepared from nitrate solutions has been investigated. pH control causes the BET surface area of gamma-alumina to vary between 180 and 410 m(2)/g and determines the extent of microporosity within the aluminas. Particle sizes derived from XRD data are compared to values quoted in the open literature. Strong retention of nitrate ion was found for precipitation at pH below the PZC; at the same time, the precipitate density was sharply lowered. However, nitrate retention did not adversely affect the development of surface area following heat treatment.