Biodiesel　is　one　of　the　most　important　substitutes　for　diesel　oil.　This　work　reports　the　use　of　near　Infrared　Spectroscopy　(NIR)　to　estimate　the　kinematic　viscosity　value　of　biodiesel-diesel　blends.　Partial　least　squares　models　were　developed　using　data　of　different　spectra　regions　and　different　pre-processing　methods　were　employed　for　developing　the　calibration　models.　The　results　indicate　that　NIR　can　be　used　in　biodiesel-diesel　blends　properties　detecting.