The phase evolution and magnetic properties of Pr2Fe23B3 and Pr2(Fe0.975Ti0.025)23B3 melt-spun ribbons have been investigated. For Pr2Fe23B3 spun at 25 m/s, the magnetically hard Pr2Fe14B phase coexists with α-Fe, Pr2Fe23B3, and Fe3B when annealed at temperatures above 700 °C, while merely two phases, namely, Pr2Fe14B and α-Fe, coexist if annealed above 800 °C. Because of the excessive annealing, these ribbons exhibit large grain sizes that lead to low Br and iHc values. A slight substitution of Ti for Fe in Pr2(Fe0.975Ti0.025)23B3 suppresses the formation of metastable Pr2Fe23B3 phase and leads to the presence of large amount of Pr2Fe14B and α-Fe phases of fine grain sizes in the matrix even at low annealing temperature (i.e., TH = 650 °C). As a result, the magnetic properties improve remarkably from Br = 6.7 kG, iHc = 1.5 kOe and (BH)max = 1.7 MG Oe of the ternary Pr2Fe23B3 to Br = 9.9 kG, iHc = 5.7 kOe and (BH)max = 15.0 MGOe of the Pr2(Fe0.975Ti0.025)23B3. © 2003 American Institute of Physics.