John R. Froines (born 1939) is a chemist and anti-war activist.
He is noted as a member of the Chicago Seven, a group charged with involvement with the riots at the 1968 Democratic Convention in Chicago. Froines, who holds a Ph.D. in Chemistry from Yale, was charged with interstate travel for purposes of inciting a riot and with making incendiary devices. He and Lee Weiner were the only two defendants to be acquitted by the jury on both of the counts charged against them and contempt of court findings by Judge Julius Hoffman were rejected in their entirety after an appeal.
While still waiting for acquittal in the early 1970s, Froines was on the faculty at Goddard College in Vermont, where he taught chemistry. He later served as the Director of Toxic Substances at the federal Occupational Safety and Health Administration. Froines also served as chair of the California Scientific Review Panel on Toxic Air Contaminants for nearly 30 years before resigning in 2013 amid claims that he conducted independent research with the panel while maintaining ties to other scientists who disapproved of the chemicals he was evaluating, creating a conflict of interest. He retired in 2011  from the UCLA School of Public Health, in the Department of Environmental Health Sciences.