Light curve analysis of a new W UMa system GSC 3581-1856

New BVRI photometric observations covering seven minima times for the eclipsing binary GSC 3581-1856 were presented. The light curves in BVRI colours were analysed by using PHOEBE code for the system parameters. New minima times were used in revising the light elements. The system is found a W-type contact binary with mass ratio of q = 1.3362 ± 0.0042 and a fill out parameter of f = 16.89 ± 3.17% . The smaller and less massive component was found hotter component (T1  ≃  5590 K). Lower temperature (T2 = 5295 K) of the mass accreting more massive component is probably due to a disk or envelope around this star. The original temperature of the more massive secondary component would be at least T2  ≃  5590 K. The preliminary absolute dimensions (M1 = 0.78 ± 0.01 M⊙, M2 = 1.05 ± 0.01 M⊙, R1 = 0.92 ± 0.10 R⊙, R2 = 1.05 ± 0.20 R⊙, L1 =0.86 ± 0.20 L⊙ and L2 = 1.00 ± 0.20 L⊙) indicate a relatively young marginal contact binary for GSC 3581-1856 system. The present luminosity of the less massive but hotter component would be not much different from its main sequence luminosity, and thus its original mass was estimated to be slightly more than one solar mass. This means it could be transferred and/or lost about 30% of its original mass which place the system in relatively young system in contact phase.