  In the optical spectra of the cold post-AGB supergiant GSC 04050$-$02366,
obtained with the 6-meter BTA telescope with a spectral resolution of
R$\ge$60000 on arbitrary dates over 2019$\div$2021, a radial velocity
variability is found. Heliocentric Vr based on the positional measurements of
numerous absorptions varies from date to date with a standard deviation of
$\Delta$Vr$\approx$1.4 km/s about the average value of Vr=24.75 km/s, which may
stem out of the low-amplitude pulsations in the atmosphere. The spectra of the
star are purely absorption type, there are no obvious emissions. Intensity
variability of most of absorptions and Swan bands of the C$_2$ molecule was
discovered. A slight asymmetry of the H$\alpha$ profile is observed at some
observation dates. The position of H$\alpha$ absorption core varies within
27.3$\div$30.6 km/s. Splitting into two components (or asymmetry) of strong
low-excitation absorptions (YII, ZrII, BaII, LaII, CeII, NdII) was found. The
position of the long-wavelength component coincides with the position of other
photospheric absorptions, which confirms its formation in the atmosphere of the
star. The position of the shortwave component is close to the position of the
rotational features of Swan bands, which indicates its formation in the
circumstellar envelope expanding at a velocity of about Vexp=16 km/s.
