Kinetics of the solid-state reaction between naphthalene and 2,4-dinitrophenol have been studied at different temperatures (30-50 degrees C), and it was found that naphthalene diffuses toward 2,4-dinitrophenol. When naphthalene enters into the crystal lattice of 2,4-dinitrophenol, a 1:1 addition compound is formed with an orthorhombic crystal lattice, and the unit cell volume is much higher than the sum of the unit cell volumes of the components. As a result of this, cracks are formed and the reaction goes to completion. Computer calculations have shown that charge-transfer interaction occurs between the two components during the reaction.