The epoxy-diamine cure process was studied. We found that the mechanism can be described in three steps : i) initiation up to 20-25% of conversion. ii) autoacceleration and iii) inhibition. It has been observed that after the initiation there is a clear autoacceleration effect which has been explained in terms of free volume, considerations : the volume occupied by the products of reaction diminishes the available volume increasing the "local concentration" of the reactants and therefore the rate of reaction. The reaction was followed by FTIR(near infrared) as the main technique. We used a purified epoxy resin as well as phenyl glycidyl ether cured with m-xylenediamine.