A temporarily stable aqueous slip of Y-alpha-SiAlON precursors powders (Si(3)N(4), Al(2)O(3), Y(2)O(3), and AlN powders) was successfully prepared using an AlN powder thermo-chemically treated against hydrolysis (AlN-TC). Aqueous suspensions of AlN-TC and an Si(3)N(4)-based powders' mixture (Si(3)N(4)/Y(2)O(3)/Al(2)O(3)) proved to have long-term stability under separate deagglomeration by ball milling. However, the kinetic stability decreased when the two suspensions were mixed in the required proportion to obtain a precursor Y-alpha-SiAlON composition. This work aims at understanding better the aging phenomena and evaluating the feasibility of using aqueous processing to fabricate Y-alpha-SiAlON ceramics. The pH and rheological behavior of the suspensions were monitored along the time. The effects of drying conditions (room temperature or humidity-controlled chamber) of slip-cast samples on the crystalline phases and oxygen contents before and after sintering were evaluated. Drying under a moisture-rich atmosphere favored hydrolysis of AlN and the appearance of beta-SiAlON as the main phase after sintering. The results allowed concluding that there is a time frame within which Y-alpha-SiAlON ceramics can be fabricated from aqueous suspensions.