We consider a thermodynamically consistent model for the evolution of thermally conducting two-phase incompressible fluids. Complementing previous results, we prove additional regularity properties of solutions in the case when the evolution takes place in the two-dimensional flat torus with periodic boundary conditions. Thanks to improved regularity, we can also prove uniqueness and characterize the long-time behavior of trajectories showing existence of the global attractor in a suitable phase-space.Keywords: Cahn-Hilliard, Navier-Stokes, incompressible non-isothermal binary fluid, thermodynamically consistent model, regularity of solutions, long-time behavior.MSC 2010: 35Q35, 35K25, 76D05, 35D35, 80A22, 37L30. * All the authors are partially supported by the GNAMPA (Gruppo Nazionale per l'Analisi Matematica, la Probabilità e le loro Applicazioni) of INdAM (Istituto Nazionale di Alta Matematica), through the project GNAMPA 2016 "Regolarità e comportamento asintotico di soluzioni di equazioni paraboliche" (coord. Prof. S. Polidoro) and by the University of Modena and Reggio Emilia through the project FAR2015 "Equazioni differenziali: problemi evolutivi, variazionali ed applicazioni" (coord. Prof. S. Polidoro) 1 energy configurations of the phase variable. Here we will assume that F is smooth and has a powerlike growth at infinity. Finally, the function κ(ϑ) in (1.5) denotes the heat conductivity coefficient, assumed to grow at infinity like a sufficiently high power of ϑ (see (K1) below).The system is highly nonlinear and contains complicated coupling terms; however these features arise naturally and are directly related to the thermodynamical consistency of the model. In particular, the quadratic terms on the right hand side of (1.5), which constitute the main difficulty in the mathematical analysis, describe the heat production coming from dissipation of kinetic and chemical energy, respectively. We may also note that transport effects are admitted for all variables in view of the occurrence of material derivatives in (1.2), (1.3) and (1.5). In order to avoid complications related to interactions with the boundary, we will assume here Ω = [0, 1] × [0, 1] to be the two-dimensional flat torus. Correspondingly, we will take periodic boundary conditions for all unknowns.System (1.1)-(1.5) has been first introduced in [8] and can be considered as a coupling between the Navier-Stokes equations and the thermodynamically consistent model for phase transitions proposed by M. Frémond in [3] and extensively studied in recent years (see, for instance, [6,15,16,17,23] and the references therein, we also quote [7] for applications to elastoplasticity with hysteresis and [10] for liquid crystals). Other nonisothermal models for phase-changing fluids can be obtained by linearization around the critical temperature, which simplifies the mathematical analysis but gives rise at least to a partial loss of thermodynamical consistency.A mathematical study of (1.1)-(1.5) has been first attempted in [8,9], which refer to the threeand...