The search for an alternative to the conventional gas-based refrigeration technique has led to the discovery of magnetic refrigeration, which has become very promising recently. The growth of this technique depends on the availability of potential solid state magnetic materials, which act as refrigerants. The underlying property of magnetic refrigerants is the magnetocaloric effect (MCE), which is measured in terms of isothermal magnetic entropy change (DeltaSm) and/or adiabatic temperature change DeltaTad). In recent years, there have been a large number of studies in various magnetic materials for finding out their suitability as potential refrigerants. Large MCE is generally observed in those materials which undergo magneto-structural transition and/or first order magnetic transitions (FOMT) [1,2]. In this regard, it has been found that hole-doped lanthanum manganites La1-x(Ca, Sr, Ba)xMnO3 with x=0.3 (i.e. Mn3+/Mn4+=7/3) give strongest magnetoresistance (MR) and magnetocaloric (MC) effects. This is due to the dominancy of Mn3+/Mn4+ ferromagnetic (FM) interactions besides antiferromagnetic (AFM) interactions associated with Mn3+/Mn3+ and Mn4+/Mn4+ pairs. Among hole-doped manganites, La0.7Ca0.3MnO3 (LCMO) has received particular attention because its colossal MR and MC effects occurring around the Curie temperature (TC) can be controlled to shift towards room temperature [3]. The FM-PM transition of LCMO is discontinuous and followed up with structural changes, which is known as a first-order magnetic phase transition (FOMT) [4]. This discontinuous phase transition can be rounded to a continuous one, known as a second-order magnetic phase transition (SOMT), based on quenched disorder upon the doping, finite-size effect, and high applied fields [5]. Though many works focused on FOMT and SOMT features in LCMO-based materials, the crossover region between first and second-order phase transitions and some related physical properties have not been widely studied. As mentioned above, the transition type occurring in this material can be tuned by doping and/or finite-size effect. In the present project, compounds based on LCMO with Ni chemical doping will be prepared using physical (standard solid state reaction) and chemical routes such as the Pechini method [6]. The critical behavior and MCE will be investigated in these compounds. It is important to signalize that the synthesis of the compounds using the wet chemistry route, known as Pechini, method allows one to obtain grain sizes in the nanometric range. In this regard, it is widely known that the physicochemical properties of nanostructured systems can be very distinct from those observed in conventional bulk systems [7]. The observed differences can be related to surface effects, since nanostructured systems have a considerable surface/volume grain ratio, much higher than the bulk counterpart, causing a large difference in the electronic and magnetic properties [8,9]. Interestingly, the resistivity of manganites shows a metal-semiconductor transition at T=Tms near to its TC. Magnetic field application decreases resistivity and shifts Tms towards higher temperatures. The MR shows a peak around TC and increases in value with the applied magnetic field. A similar behavior has been observed between magnetic entropy change DeltaSM, resistivity and MR around TC, which is attributed to the spin order/disorder feature that plays a main role in the magnetocaloric-transport correlation. Hence, transport measurements should be performed in order to study the cited correlation.