The photoacoustic calorimetry technique is described in detail, as a tool for high precision thermochemistry studies of transient species. The need for a method to assess a photoacoustic calorimeter is underlined, and the reaction of phenol with di-tert-butyl peroxide is proposed as a possible candidate. The method for determining the O-H bond dissociation enthalpy in phenol from the photoacoustic experiments is discussed and a proposed "direct" method is compared with an "indirect" method established in the literature. The obtained value of (359.5 +/- 5.2) kJ.mol(-1) is in good agreement with the literature result obtained by the "indirect" method.