We aim to couple the electrospinning in-line with solution chemistry to fabricate novel crosslinked polymer nanofibers. Poly(vinyl alcohol) (PVA) was used as a model polymer due to its high amount of hydroxyl groups. To obtain ideal parameters for electrospinning, pure PVA was explored primarily. To gain crosslinked fibers, PVA was first crosslinked partially with glutaraldehyde (GA) followed by transferring this precursor to a long hot tube which was used as reactor and then electrospun right before gelation. The preheating time and tube-passing time were determined with viscometer and rheometer. The reactive as-spun fibers could maintain their original morphology after water immersion due to their high crosslinking degree. The thermal stability and mechanical property of reactive as-spun fibers were improved drastically compared with pure and GA vapor crosslinked PVA fibers. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012