In the title Schiff base, C(14)H(10)N(2)OS, the azomethine double bond is in an E configuration; the benzothiazolyl ring (r.m.s. deviation = 0.007 Å) is coplanar with the phenyl-ene ring (r.m.s. deviation = 0.007 Å), the two rings being slightly bent at 2.6 (1)°. The hy-droxy H atom forms an intra-molecular hydrogen bond to the imino group. The bond dimensions of the monoclinic modification are similar to those of the ortho-rhom-bic modification [Liu et al. (2009 ▶). Acta Cryst. E65, o738].