Condensation of PhOH with CH(2)O was carried out in aq. alk. soin. at 60 degrees C and 80 degrees C, NaOH catalyst concn. 0.2-1 cg/ g and CH(2)O:PhOH mole ratio 1.5-3.5 for 270 min and followed by photometry at wave length 410 nm to check the applicability of the method for studying the reaction kinetics. The Box-Behnken exptl. design was used for the study. Regression equations were derived and verified expti. by anal. detn. of free CH(2)O, and PhOH contents as well as the absorbance. The expti. data agreed well with the calcd. ones. The method developed was recommended for controlling the process for manufg. the PhOH-CH(2)O resins under lab. and com. conditions.