Abstract : Photothermoelectric (PTE) calorimetry was applied for the first time for thermal characterization of liquids. Both back and front detection configurations, together with the thermal-wave resonator cavity (TWRC) scanning procedure, have been used in order to measure the thermal diffusivity and thermal effusivity of a particular magnetic nanofluid carrier liquid—transformer oil, surfactant—oleic acid, nanoparticles’ type—$$\hbox {Fe}_{3}\hbox {O}_{4}$$Fe3O4.The investigations were performed as a function of the nanoparticles’ concentration. Small increases of thermal diffusivity (from $$9.06\times 10^{-8}\,\hbox {m}^{2}{\cdot } \hbox {s}^{-1}$$9.06×10-8m2·s-1 up to $$9.84\times 10^{-8}\,\hbox {m}^{2}{\cdot } \hbox {s}^{-1})$$9.84×10-8m2·s-1) and thermal effusivity (from $$450\,\hbox {W}{\cdot } \hbox {s}^{1/2}{\cdot } \hbox {m}^{-2}{\cdot } \hbox {K}^{-1}$$450W·s1/2·m-2·K-1 up to $$520\,\hbox {W}{\cdot } \hbox {s}^{1/2}{\cdot } \hbox {m}^{-2}{\cdot } \hbox {K}^{-1})$$520W·s1/2·m-2·K-1) with increasing concentration of $$\hbox {Fe}_{3}\hbox {O}_{4}$$Fe3O4 nanoparticles (from 0 up to 0.623 mg $$\hbox {Fe}_{3}\hbox {O}_{4}/\hbox {ml}$$Fe3O4/ml fluid) were observed. The comparison with the photopyroelectric (PPE) method shows that PTE and PPE give similar results but, for the moment, PPE is more accurate. © 2015, Springer Science+Business Media New York.