  We model the spectra of two brown dwarfs observed with the low resolution
spectropolarimeter LRIS (Keck observatory) during several rotational phases in
order to infer their magnetic properties. The spectra modeled include the
intensity signal (Stokes I/Ic) as well as the polarimetric signals (Stokes
Q/Ic, U/Ic, and V/Ic), all coming from the 0-0 vibrational band of the CrH
molecule at approx. 8610 A. In order to model the Stokes profiles, we solve a
set of the radiative transfer equations for the CrH transitions in the presence
of an external magnetic field. We present the upper limits for the magnetic
field strengths for the objects observed, based on the modeling of the
intensity signal I/Ic and the signal-to-noise information only. The proper
modeling of the polarimetric signals, that requires more careful data
reduction, is underway. Nevertheless, our preliminary results show a hint for
kG magnetic fields for both brown dwarfs, that is in a good agreement with the
result obtained from the simultaneous radio, H{\alpha} and X-Ray observations
of one another radio pulsating brown dwarf.
