Hydrothermal reactions need high temperature (T) and Pressure (P). T would be effective for kinetics via KT. However P would affect as Log P like Concentration(C) as Log C, where C can be changed in 5-8 order of magnitudes but P is difficult to change even 2-3 orders. Particularly in “Autoclaves” pressure increases would be more difficult and costly than temperature. Thus, autoclaves seems not to be always the best choice of hydrothermal reactor. Pipe-line or capillary tube may be better for continuous production. Moreover, most of Hydrothermal/Solvothermal reactions can occur at the interface between liquids and solids, therefore, they can be activated by Chemically, Electrochemistry, Sono-, Mechano-, Microwave-, Laser-, Plasma-,etc., where those activation could be locally, 1D, 2D and 3D patterning can directly form in Solution. These locally activated solution processes will be developed widely and successfully. Complex formation in solution species and solid surfaces should be considered.