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MFe 2 O 4 (M = Co, Fe, Mn) compounds were synthesized using hydrothermal treatment in the presence of medicinal cotton. Two sets of nanoparticles were produced for each composition and subsequently characterized by XRD, TEM and SEM. The nanoparticles obtained from the solution display the expected spinel structure and different mean sizes (below 16 nm); the nanoparticles embedded in cotton were subjected to a calcination process for cotton elimination. Regarding these calcinated samples, the spinel structure was maintained for CoFe 2 O 4 , a mixture of phases was identified for the M = Mn sample and, in the case of iron, the magnetite phase was converted to hematite (a-Fe 2 O 3 ). After cotton elimination the samples exhibit a morphology which evidences the role of cotton as a template. To evaluate the quality of the nanoparticles for hyperthermia, SQUID magnetometry and Mössbauer spectroscopy were used to perform the magnetic characterization of all products, and the specific loss power (SLP) was determined by induction heating measurements. All the ferrite NP obtained by hydrothermal synthesis in the presence of cotton display good hyperthermia performance. MnFe 2 O 4 nanoparticles exhibit the highest SLP value, 90 W g À1 , followed by Fe 3Àx O 4 , and CoFe 2 O 4 . In the case of CoFe 2 O 4 , the specific loss power of the NP obtained after cotton elimination is enhanced by 50% which is explained by the NP morphology adopted from the cotton template during the synthesis.