Poly(I-oxotrimethylene) (ECO) was dissolved in aqueous calcium chloride (CaCl2)/zinc chloride (ZnCl2) composite metal salt solutions, and the solutions had phase-separation temperatures greater than 0 degrees C. A higher proportion of CaCl2 with respect to ZnCl2 increased the phase-separation temperature of the ECO solutions. When wet spinning was carried out with a coagulation bath at 2 degrees C, an ECO solution with a higher phase-separation temperature tended to produce greater ECO fiber strength. Therefore, a higher phase-separation temperature resulted in coagulated filaments with a denser and more homogeneous cross-sectional structure. When the metal salt concentration of the coagulation bath was increased with an ECO solution with a phase-separation temperature of 22 degrees C and a coagulation-bath temperature of 2 degrees C, the strength of the ECO fibers tended to be lower. Although little difference was observed in the uniformity of the fiber cross sections, a higher metal salt concentration in the coagulation bath facilitated greater spherical growth of the coagulated particles. Large, spherical coagulated particles promoted defects during drawing and thus lowered the strength of the ECO fibers. (c) 2005 Wiley Periodicals, Inc.