© 2016 Owned by the authors, published by EDP Sciences. The particle-hole dispersive optical model developed recently is applied to describe properties of high-energy isoscalar monopole excitations in 208Pb. We consider, in particular, the double transition density averaged over the energy of the isoscalar monopole excitations in a wide energy interval, which includes the isoscalar giant monopole resonance and its overtone. The energy-averaged strength functions of these resonances are also analyzed. Some corrections to the calculation scheme are formulated to restore the model unitarity.