Flame spray pyrolysis technology makes use of the high chemical activity of a flame. A metal salt aqueous solution is used as the material to be treated and is atomized into a furnace by high pressure spraying. The solvent in the sprayed minute liquid droplets evaporates, pyrolysis occurs, and then solid particles are generated. We focused on the spray pyrolysis method for preparation of LiMn2O4 for use as the positive poles of lithium-ion secondary batteries. We utilized a gas combustion system as the heat source that is characterized by the fact that its operation costs can be much less than that of conventional electric heating systems. On the other hand, in-flame treatment technology uses the high-temperature environment within a flame. In this method, the material to be treated, fine metal and ceramic powders, is introduced directly into an oxygen flame to be melted. The technology related to in-flame melting of silica, which has already been established, is a typical example of this type of technology, which is based on the principle that a material is melted within a flame and spheroidized as a result of its surface tension. Use of a fine powder as the material to be treated enables wide application of this technology.