The aim of this study is to obtain and characterize of alginate-based membranes, as well as to choose the most suitable membrane type for the transdermal release of methotrexate. The paper presents the synthesis of four types of membranes based on alginate to which are added other copolymers (Carbopol, Tween, and Polyvinylpyrrolidone) as well as other components with different roles. Membranes and binary mixtures made between the components used in membrane synthesis and methotrexate are analyzed by thermogravimetric techniques, FTIR and UV spectroscopic techniques as well as SEM. The analyses aim to establish the type of membrane most indicated in the use of the controlled release of methotrexate, namely those membranes in which there are no interactions that could inactivate the active substance. Following these studies, it was concluded that membranes obtained from alginate/alginate and Tw can be used for methotrexate release. The membrane obtained from alginate and carbopol was excluded from the beginning because it is not homogeneous. Regarding the AGP-MTX membrane, it presents interactions with the active substance, carboxylate group interactions argued by TGA and FTIR studies, and interactions that occur in aqueous medium.