β-FeSi 2 bulk single crystals were grown using a temperature gradient solution growth (TGSG) process in Sb solvent. The microstructural and electrical properties of the β-FeSi 2 were then characterized. Rectangular-shaped single crystals were basically obtained with facetted crystallographic planes having the predominant growth direction of β-FeSi 2 [011]. No evidence for the formation of 90 o order domains around the a-axis, domain boundaries and long period structures was observed by transmission electron microscopy (TEM). It was also found that the crystal shows n-type behavior, and that the donor ionization energy deduced from the temperature dependence of the electron concentration is approximately 0.12-0.15 eV. The nature of defects will be discussed along with the photoconductivity and the electron spin resonant (ESR) measurements.