AbstractHigh resolution FT spectroscopy has been applied to investigate a YAB: Ho3+ (1 mol%) single crystal, grown by the top‐seeded flux method, in the wave number 4000–25000 cm–1 and temperature 9–300 K ranges, respectively. The complex Ho3+ (4f10) non‐Kramers ion transitions from the ground 5I8 to the excited 5I7, 5I6, 5I5, 5I4, 5F5, 5S2, 5F4, 5F3, 5F2, 3K8, 5F1 + 5G6, and 5G5 manifolds were analyzed. The low‐temperature high resolution spectra of the investigated manifolds show for many electronic transitions hyperfine structures related to the Ho3+ nuclear magnetic moment. The experimental data are fitted by a single ion Hamiltonian and the crystal field parameters are obtained. The results are compared with those previously published for other rare earths in the same matrix. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)