The application of calorimetry to the dimerization of isoprene yielded various results that depend on the homogeneous palladium catalyst, its composition, the solvent selected and, not least, the concentration of isoprene. The influences of all the variables were optimized with respect to the turnover and the ratio of the two main products that are the head-head or head-tail configurations of dimeric isoprene. The products are of interest in perfumery.