In the near future, companies will face the need to produce low formaldehyde emission resins, i.e., not above the emission level of natural wood. However, for producing this new generation of urea-formaldehyde resins (UF), it is necessary to optimize the synthesis process. This work describes an optimization procedure for UF resin synthesis, following an alkaline-acid process, focusing on the conditions of the condensation step. A design of experiments methodology was employed to optimize the 3 selected factors (number of urea additions, time span between urea additions, and condensation pH), in order to produce particleboards with maximum internal bond strength and minimum formaldehyde release. The condensation pH played a significant role in increasing the Internal Bond (IB) strength and reducing the Formaldehyde Emission (FE). The sequential addition of urea also has a noticeable influence on resin performance. Optimum conditions for production of UF resins have been proposed and tested by the response surface methodology using the desirability function. (C) Koninklijke Brill NV, Leiden, 2010