Studies of the author on the dynamics of ion-molecule reactions using the crossed beam scattering techniques are reviewed. Experimental methods used in these single-collision studies are described. Results of investigation of selected reactions illustrate the basic features of the direct stripping mechanism and of complex formation in ion-molecule reactions. Reactions which proceed by several collisional mechanisms simultaneously are discussed. Dynamics of chemical reactions of dications with molecules which lead to the formation of two singly charged products of a rather high kinetic energy are described.