Enhancement of thermal performance of concrete wall is nowadays of great importance in reducing the operational energy demand of buildings. We developed a new kind of inorganic coating material based on SiO2 - Al2O3 -rich minerals and Portland cement (PC) powder. The finely pulverized mineral powder with the particle size distribution (PSD) of 0.4-40 mu m was mixed with the vehicle solvent containing some agents, cement powder with PSD of 2-100 mu m, and water in the certain weight ratio, producing the colloid solution. After application within 2 h to the plaster layer of concrete wall and sufficient long hardening period of over three months, the coating layer of 0.6-1.0 mm thickness was observed to become a densified ceramic. Powder X-ray diffraction (XRD) experiments were performed to identify the crystalline components of minerals, cement and ceramic coating powders. Three- and two-dimensional surface morphologies and chemical compositions of coating material were obtained with the optical interferometer and scanning electron microscope (SEM) equipped with an energy dispersive X-ray analyzer (EDX). These XRD and SEM/EDX analyses demonstrated obviously that the coating layer is mainly composed of the calcium-silicate-hydrate (C-S-H) and the calcium-aluminate-hydrate (C-A-H) ceramics with the relatively small number of closed pores (10% porosity) compared with the cement mortar and concrete layers. Two-step hydrations of cement and subsequently SiO2 - Al2O3 promoted by the alkali product Ca(OH)(2) were proposed as the main mechanism of ceramic formation.