BaZrO3 nanofibers were electrospun from a 0.25 M metal cation solution containing barium acetate and zirconium 2,4-pentadionate dissolved in glacial acetic acid. Polyvinylpyrrolidone was added to increase the solution viscosity and allow formation of hollow fibers during electrospinning. Microstructural evolution during thermal annealing at temperatures between 600 degrees C and 1400 degrees C was studied revealing crystal growth evolution. Strong grain coarsening is observed above 1200 degrees C, leading to linear and branched nanoparticle chains originating from the finer initial hollow nanofibers. Faceting of the nanoparticles occurs in the low-energy surfaces. On the other hand, grain boundaries are planar and follow the same facet planes as the nanoparticles. High resolution transmission electron microscopy reveals no general epitaxial relationship at the interface with the exception of a minor amount of low angle grain boundaries.