The　influence　of　calcination　on　antimony-doped　tin　oxide　(ATO)　powders　was　studied.　The　x-ray　diffraction　was　used　to　characterize　the　grain　size　and　phases　of　ATO　powders.　The　results　show　that　the　grain　size　increases　with　increasing　calcination　temperature　while　the　powders　retain　tetragonal　rutile　structure　of　SnO2.　The　transmission　electron　microscopy　micrographs　show　that　all　particles　are　in　spherical　shape　and　particle　size　increases　with　increasing　the　calcination　temperature　too.　Compared　with　Sb2O3,　Sb2O5　has　the　lower　standard　free　energy　of　formation　and　therefore　Sb　in　the　SnO2　lattice　is　Sb5+.