La0.7KxCa0.3-xMnO3 (x = 0, 0.05, 0.1) perovskites were prepared by sol-gel method. The K-doped effect was determined by the structural, magnetic, and magnetocaloric properties of the compounds. In the crystal structure of K-doped La0.7Ca0.3MnO3, Mn-O-Mn bond angle slightly increases with K addition. The transition shifts the range of 270-320 K when the K is added in La0.7Ca0.3MnO3. The Curie temperature increases from 251 to 288 K with increasing K amount. The maximum magnetic entropy change was found to be 2.7 J kg(-1) K-1 at 283 K under a magnetic field change of 2 T for the La0.7K0.05Ca0.25MnO3. The relative cooling powers (RCPs) in the La0.7KxCa0.3-xMnO3 (x = 0, 0.05, 0.1) samples were calculated to be 103, 133 and 88 J kg(-1), respectively.