The reactions of ethanol and 1-propanol on a 1.3 monolayer Co overlayer was investigated in an effort to understand the reactivity of Co thin films deposited on Mo(110). Electron energy loss data show that O-H bond scission to afford the alkoxide occurs by 275 K for both alcohols on a Co monolayer deposited on Mo(110). Carbon monoxide and H-2 are the major gaseous products identified by temperature-programmed reaction, and residual carbon and oxygen are detected after heating to 760 K. In addition to CO and H-2, ethanol reaction produces acetaldehyde, methane, and ethylene, while 1-propanol reaction produces propanal, ethylene, and propene. Selective deuteration at the beta position precludes aldehyde production, demonstrating that beta C-H bond cleavage is the rate-limiting step for aldehyde formation and that there is a delicate balance between the nonselective and selective dehydrogenation pathways. Isotopic labeling also shows that methane production from ethanol and ethylene from 1-propanol occur by selective beta C-C bond scission. The reactions of ethanol and 1-propanol on the Co overlayers are compared with those of 2-propanol and methanol. The activity of Co thin films on Mo(110) for both selective and nonselective dehydrogenation allows alcohol reaction pathways to be controlled by minor changes in structure and bonding.