Hot core chemistry, characterized by the evaporation of icy mantle molecules from dust grains and subsequent gas-phase chemistry, seems ubiquitous in hot, dense clouds. Hot core molecules have been observed, not only in high-mass star-forming regions, but also in protoplanetary disks, shocks in young stellar outflows, and so on. Here, we study grain-surface chemistry and chemistry in hot gas in disks and outflows. Our results suggest that observations of molecular lines by the forthcoming ALMA and other facilities will give us information on, for example, grain-surface chemistry in the outer disk, turbulent mixing in the inner disk, and the physical and chemical conditions at the launching points of outflows.