  Submicron powder of CrO$_2$ was prepared by hydrothermal synthesis method
from chromium trioxide. Particles obtained were of rounded form with mean
diameter about 120 nm. The powder (stabilized with thin surface layer of
\beta-CrOOH) has been characterized by structural, X-ray and magnetic
measurements. The powder (with Curie temperature about 385 K) was cold-pressed
and its transport and magnetotransport properties have been measured in the
temperature range 4--450 K in magnetic field up to 1.6 T. The samples studied
is characterized by non-metallic temperature behavior of resistance and large
negative magnetoresistance (MR) in low temperature range. At T=5 K the MR
magnitude has been -17% at H=0.3 T and -20% at H=1.4 T. Its magnitude decreased
fast with increase in temperature reducing to 0.3% and less for T>200 K. It is
shown that this MR behavior is inherent for a system of magnetic grains with
spin-dependent intergrain tunnelling. Some peculiarities of MR behavior in
low-temperature range (below 40 K) can be associated with percolating character
of tunnelling conductivity of this granular system under conditions of
availability of only few conducting current paths through the sample.
