We have reported the sol-gel synthesis and microstructural, magnetic, magnetocaloric, and critical behaviors of La(0.7)Ba(0.15)Sr(0.15)CoO(3)cobaltite. The XRD data refined by Rietveld technology confirms that a sample has a pure perovskite phase with rhombohedral structure. We tested the magnetization curve near the phase transition temperature (T-C) from ferromagnetic (FM) to paramagnetic (PM), and made the Arrott diagram which confirmed the existence of the secondary phase transition. The obtained magnetic constants from hysteresis loop offer to the sample the possible use in some interesting technological applications. TheM(mu H-0,T) isothermal magnetizations have been analyzed to estimate the critical exponents (beta,gamma, and delta). We found that beta exponent is close to that of the mean-field model; however,gamma and delta exponents belong to an unconventional model. The reliability of the estimated critical exponents was checked from the magnetic field variations of the magnetic entropy change (- Delta S-m) and the relative cooling power (RCP).