A mesofluidic reactor performs a chemical reaction of a starting material. A liquid phase starting material is introduced into a spraying head equipped with an ultrasound generating piezoelectric crystal unit. An inert/reagent gas feeds into the spraying head, connected to a reactor tube arranged within a thermally insulated multi-zone heating unit. For solid phase, an inert/reagent gas is introduced into a solids container connected to a spraying head equipped with an ultrasound generating piezoelectric crystal unit. The spraying head connects to a reactor tube arranged within a thermally insulated multi-zone heating unit. In either case, a reactor tube outlet connects to a cooled product trap to collect conversed substances. The spraying head generates a particle size distribution with nano and micro sized particles for the liquid phase and nano, micro or larger particles for the solid phase. The inert/reagent gas is preheated over the piezoelectric crystal unit's surface.