Photometric BV light curves of BO CVn obtained in 1992 and new times of minima are presented. The primary minimum shows a transit, whereas the secondary minimum, shows an occultation. The system may be classified as an A-type W UMa system. A complete study of minima allows one to detect a possibly increasing period by about 0.037 s/yr. This indicates that the conservative mass transfer rate from the less massive component to the more massive one is 1.57 10(-10) M-circle dot/yr. Because of the variable period, the new ephemeris is determined for future observations. Using the Wilson-Devinney code a simultaneous solution of the B and V light curves is also performed. The analysis shows that the system is in a contact configuration with q = 0.205 +/-0.001 and fillout factor- (f) = 0.18, T-1 = 7240 K(fixed), T-2 = 7150 +/- 10 K. The high orbital inclination i = 87 degrees .54 +/-0.26 was confirmed by photometric observations of the secondary minimum.