  This paper describes a multiwavelengh optical study of chromospheres in two
X-ray/EUV selected active binary stars with strong H_alpha emission, V789 Mon
(2RE J0725-002) and GZ Leo (2RE J1101+223). The goal of the study is to
determine radial velocities and fundamental stellar parameters in
chromospherically active binary systems in order to include them in the
activity-rotation and activity-age relations. We carried out high resolution
echelle spectroscopic observations and applied spectral subtraction technique
in order to measure emission excesses due to chromosphere. The detailed study
of activity indicators allowed us to characterize the presence of different
chromospheric features in these systems and enabled to include them in a larger
activity-rotation survey. We computed radial velocities of the systems using
cross correlation with the radial velocity standards. The double-line spectral
binarity was confirmed and the orbital solutions improved for both systems. In
addition, other stellar parameters such as: spectral types, projected
rotational velocities (vsini), and the equivalent width of the lithium LiI
6707.8 AA absorption line were determined.
