  Although magnetic fields have been discovered in ten massive O-type stars
during the last years, the origin of their magnetic fields remains unknown.
Among the magnetic O-type stars, two stars, HD36879 and HD57682, were
identified as candidate runaway stars in the past, and theta^1 Ori C was
reported to move rapidly away from its host cluster. We search for an
explanation for the occurrence of magnetic fields in O-type stars by examining
the assumption of their runaway status. We use the currently best available
astrometric, spectroscopic, and photometric data to calculate the kinematical
status of seven magnetic O-type stars with previously unknown space velocities.
The results of the calculations of space velocities suggest that five out of
the seven magnetic O-type stars can be considered as candidate runaway stars.
Only two stars, HD155806 and HD164794, with the lowest space velocities, are
likely members of Sco OB4 and NGC6530, respectively. However, the non-thermal
radio emitter HD164794 is a binary system with colliding winds, for which the
detected magnetic field has probably a different origin in comparison to other
magnetic O-type stars.
