In this paper the absorption spectra of 4f electron transitions of the system of holmium with 2-isobutylformyl-1,3-dione-indan and TX-100 have been studied by normal and derivative spectrophotometry. The molar absorptivities are 98 (at 450 nm) and 21(at 460 nm) 1.mol−1. cm−1, respectively. The use of the second derivative spectra, eliminates the interference by other lanthanides and improves the sensitivity for holmium determination. The derivative molar absorptivity is 558 1. mol−1.cm−1. The calibration graph was linear up to 25μg/ml of holmium. The relative standard deviation evaluated from ten independent determinations of 8.0 μg/ml holmuim is 1.0%. The detection limit, obtained from the sensitivity of the calibration graph and for 3 Sb(Sb= standard deviation of a blank without holmium, n = 11), was found to be 0.31 μg/ml of holmium. The quantification limit, obtained for 10 Sb, was 1.0 μg/ml of holmium. A method has been developed for determining holmium in a mixture of lanthanides by means of the second derivative spectra and the analytical results obtained are satisfactory.