Using 462fb-1 of e+e- annihilation data recorded by the Belle detector, we report the first observation of the decay Ds1(2536)+→D+π-K+. The ratio of branching fractions B(Ds1(2536)+→D+π-K+)B(Ds1(2536) +→D*+K0) is measured to be (3.27±0.18±0.37)%. We also study the angular distributions in the Ds1(2536)+→D*+KS0 decay and measure the ratio of D- and S-wave amplitudes. The S-wave dominates, with a partial width of ΓS/Γtotal=0.72±0.05±0.01. © 2008 The American Physical Society.