For the first time semi-insulating (SI) GaAs single crystals were grown by the liquid encapsulated Czochralski (LEC) method using a traveling magnetic field (TMF) system generated in a heater-magnet module (HMM). The system was developed within the framework of the KRIST (MAG) over tilde (R) project. The HMM, that generates heat and TMF simultaneously, was placed closely around the crucible inside the chamber of the industrial CI 358 puller. Before the growth experiments the induced vertical Lorentz force density F-Lz was evaluated by the weight force response of a dummy. First growth experiments at various f/phi ratios (f-frequency and phi-phase shift) were carried out. Interface morphology and temperature fluctuation strengths were analyzed by a striation technique. Etch pit density, carbon, residual impurity and EL2 degrees contents as well as electrical properties of the as-grown TMF-LEC GaAs crystals were measured. A preliminary correlation between crystal qualities and field frequency has been noticed. (C) 2009 Elsevier B.V. All rights reserved.