A study of the quench propagation velocity in coated conductors produced by various manufacturers is presented. Based on an experimental investigation of the thermal and electrical properties of the coated conductors, the longitudinal normal zone propagation velocity has been calculated as a function of the temperature and magnetic field, and for different orientations of the field with respect to the tape surface. Contrary to what observed in low-temperature superconductors, we have found that the quench propagation velocity in REBa2Cu3O7-x coated conductors is weakly affected by the magnetic field and temperature, and is mainly determined by the operating current. The longitudinal normal zone propagation velocity at a given operating current assumes comparable values in the examined coated conductors, regardless of the differences in the structural, thermal, and electrical properties. The normal zone propagation velocity in the direction perpendicular to the tape surface has also been studied, starting from experimental data of the longitudinal and transverse thermal conductivities of the coated conductors.