Metal organic vapor phase epitaxy (MOVPE) for compound semiconductors is today the most versatile technology for the making of thin film layers for complex micro- and optoelectronic devices due to its flexible and scalable nature (in the case of horizontal reactors) as a CVD technology, compared to molecular beam epitaxy (MBE) or other methods. A state-of-the-art overview on its advantages, evolution and today's scaling range from single wafer MOVPE for university and R&D application through to fully automated mass production technology of up to 95 X 2 or 20 X 4 in. wafers is provided. The materials include III-V, II-VI, SiC and others. The applications are high electron mobility transistors (HEMTs), heterostructure bipolar transistors (HBTs), lasers, vertical-cavity surface-emitting lasers (VCSELs), light-emitting diodes (LEDs), solar cells, photocathodes and others.