Extraction behaviour of rare earths, La, Dy and Y, fromhydrochloric acid mediumby di-nonyl phenyl phosphoric acid (DNPPA) has been investigated over a wide range of experimental conditions such as feed acidity, feed concentration, DNPPA concentration, diluents, temperature, stripping reagents. The slope analysismethod indicated the formation of [RE(HA₂)₃] type of neutral species in the organic phase. The extraction reaction of rare earths with DNPPA was found to be exothermic with ΔH values being −10.6 kJ/mol (La), −12.9 kJ/mol (Dy) and −17.5 kJ/mol (Y). The ΔS values were found to be −42.5 (La),−37.3 (Dy) and−43.0 (Y) J/mol K. The free energy change (ΔG) were found to be −2.2 (La), −1.6 (Dy) and −4.5 (Y) KJ/mol at 303 K. Stripping of rare earth was >90% fromrare earth loaded DNPPA by sulphuric acid (7 M) in a single contact at roomtemperature (303 K). Extraction of rare earths in different diluents followed the order: petrofin ~ dodecane > dichlorobenzene >xylene > chlorobenzene. The extraction efficiency for rare earths by DNPPA increased with increase in atomic number: La < Ce < Pr < Nd < Sm< Eu < Gd < Tb < Dy < HoY < Er < Tm< Lu. Separation factors between thesemetal ionswere calculated and compared with extractants such as di-2-ethylhexyl phosphoric acid (D2EHPA) and 2-ethylhexyl 2-ethylhexyl phosphonic acid (EHEHPA). DNPPA was found to be stable even after 10 cycles of repeated extraction/stripping operations.