  We present the results of our study of the eclipsing binary systems CSS
J112237.1+395219, LINEAR 1286561 and LINEAR 2602707 based on new CCD $B$, $V$,
$R_c$ and $I_c$ complete light curves. The ultra-short period nature of the
stars \citep{Drake2014} is confirmed and the system's periods are revised. The
light curves were modelled using the 2005 version of the Wilson-Devinney code.
When necessary, cool spots on the surface of the primary component were
introduced to account for asymmetries in the light curves. As a result, we
found that CSS J112237.1+395219 is a W UMa type contact binary system belonging
to W subclass with a mass ratio of $q=1.61$ and a shallow degree of contact of
14.8\% where the primary component is hotter than the secondary one by $500K$.
LINEAR 1286561 and LINEAR 2602707 are detached binary systems with mass ratios
$q=3.467$ and $q=0.987$ respectively. These detached systems are low-mass
M-type eclipsing binaries of similar temperatures. The marginal contact, the
fill-out factor and the temperature difference between components of CSS
J112237.1+395219 suggest that this system may be at a key evolutionary state
predicted by the Thermal Relaxation Oscillation theory (TRO). From the
estimated absolute parameters we conclude that our systems share common
properties with others ultra-short period binaries.
