A novel thermal control coating based on the thermochromism of K-doped manganite nanoparticles was developed. The nanoparticles, dispersed in a polymer matrix and cured below 200°C, showed a size distribution of 100–200 nm with a comparable stoichiometric ratio. The phase transition of the nanoparticles was observed from a ferromagnetic metallic state to a paramagnetic insulator state, with the transition temperature increasing with K doping. Coatings with and without pore defects were obtained using different polymer matrices. The emittance of the K-doped coating varied sharply with temperature, reaching a maximum variation of 0.46, which is promising for space thermal control. It was suggested that 50 wt% pigment content is sufficient to achieve a large emittance variation. Manganites, such as La$_{1-x}$D$_x$MnO$_3$, have been studied for their rich physical properties, including colossal magnetoresistance, magnetocaloric effect, and thermochromic effect. These materials have an ABO$_3$-type perovskite structure, with La and D ions at the A-site and Mn at the B-site. At optimal doping levels, they exhibit a ferromagnetic metallic state below the Curie temperature and a paramagnetic insulator state above it. The properties of these materials are influenced by structural distortions and ion radius variations, which affect the metal-insulator transition temperature, residual resistivity, and Curie temperature. It is reported that doped manganites exhibit temperature-dependent spectral characteristics between 173K and 373K. The materials show higher emittance above a certain temperature (T$_{MI}$) and lower emittance below it, a property known as thermochromism. This property can be used in intelligent thermochromic devices for spacecraft thermal control, allowing automatic adjustment of emittance based on temperature to regulate radiative heat transfer. Previous studies focused on the thermochromic behavior of bulk manganites with divalent ion doping. However, existing coatings have limited emittance variation and are often bulky or heavy, especially for spacecraft applications. Coating techniques offer a simple and low-cost solution, but the thermochromic properties of existing coatings need improvement. Divalent ion co-doping manganites can exhibit composition-controlled thermochromic behavior, and monovalent ion substitution may also improve thermochromic properties.A novel thermal control coating based on the thermochromism of K-doped manganite nanoparticles was developed. The nanoparticles, dispersed in a polymer matrix and cured below 200°C, showed a size distribution of 100–200 nm with a comparable stoichiometric ratio. The phase transition of the nanoparticles was observed from a ferromagnetic metallic state to a paramagnetic insulator state, with the transition temperature increasing with K doping. Coatings with and without pore defects were obtained using different polymer matrices. The emittance of the K-doped coating varied sharply with temperature, reaching a maximum variation of 0.46, which is promising for space thermal control. It was suggested that 50 wt% pigment content is sufficient to achieve a large emittance variation. Manganites, such as La$_{1-x}$D$_x$MnO$_3$, have been studied for their rich physical properties, including colossal magnetoresistance, magnetocaloric effect, and thermochromic effect. These materials have an ABO$_3$-type perovskite structure, with La and D ions at the A-site and Mn at the B-site. At optimal doping levels, they exhibit a ferromagnetic metallic state below the Curie temperature and a paramagnetic insulator state above it. The properties of these materials are influenced by structural distortions and ion radius variations, which affect the metal-insulator transition temperature, residual resistivity, and Curie temperature. It is reported that doped manganites exhibit temperature-dependent spectral characteristics between 173K and 373K. The materials show higher emittance above a certain temperature (T$_{MI}$) and lower emittance below it, a property known as thermochromism. This property can be used in intelligent thermochromic devices for spacecraft thermal control, allowing automatic adjustment of emittance based on temperature to regulate radiative heat transfer. Previous studies focused on the thermochromic behavior of bulk manganites with divalent ion doping. However, existing coatings have limited emittance variation and are often bulky or heavy, especially for spacecraft applications. Coating techniques offer a simple and low-cost solution, but the thermochromic properties of existing coatings need improvement. Divalent ion co-doping manganites can exhibit composition-controlled thermochromic behavior, and monovalent ion substitution may also improve thermochromic properties.