We propose a simple explanation of unconventional thermodynamical and magnetic properties observed for Sr2RuO4. Actually, our two-phase model of superconductivity, based on a straight generalization of the Ginzburg-Landau theory, does predict two jumps in the heat capacity as well as a double curve for the dependence of the critical temperature on an external magnetic field. Such theoretical previsions well agree with the currently available experimental data for Sr2RuO4. 74.20.De; 74.70.Pq; In a recent series of papers [1,2,3,4] we have succeeded in obtaining a straightforward generalizations of the original Ginzburg-Landau (GL) theory [5] in order to describe s-wave superconductors endowed with two critical temperatures, or even spin-triplet one-phase superconductors. The basic idea has been to introduce two different order parameters represented by two charged scalar fields (really only one mean field with two distinct gauge representations, see below) describing Cooper pairs with electrons bound by a weaker or stronger attractive force, respectively. The resulting theoretical model is therefore able to describe superconductors with two distinct superconducting phases, since the two order parameters condensate, in general, at different critical temperatures. Peculiar thermal and magnetic properties of these kinds of superconductors have been discussed in [2,3]. Here we only mention that an additional discontinuity in the specific heat is predicted, with respect to the conventional case, when passing from a superconducting phase to the other one. Moreover, at low temperature the London penetration length for the superconductors considered is strongly reduced, and the Ginzburg-Landau parameter κ becomes a function of temperature. Instead, in temperature region between the two phase transition, κ is constant and the system behaves as a type I or a type II superconductors depending on the ratio between the two critical temperatures. Such a ratio may be as large as 4/3 [2, 3] (that is, a maximum difference of ∼ 15% between the two critical temperatures) for very large selfinteraction of the Cooper pairs with respect to the electromagnetic coupling. By allowing a suitable non-linear interaction among the two scalar fields, the same theoretical model may as well account for rotational degrees of freedom in superconductivity, that is spin-triplet superconductors with a single phase (the two mutually interacting order parameters condensate simultaneously at a same temperature). In the corresponding model, the main thermodynamical and magnetic properties of these p-wave superconductors turn out to be essentially the same as for the conventional s-wave superconductors.All the above-seen properties have prompted us to explore the possibility to use the proposed model in order to understand the intriguing properties exhibited by Sr 2 RuO 4 superconductors, which still wait for a comprehensive and solid explanation (see, for example, the review in [6]). The layered Sr 2 RuO 4 is a superconductor with a very low critical te...