24-hour monthly isoprene emissions at 1 degree x 1 degree. These are derived from Ozone Monitoring Instrument (OMI) observations of formaldehyde column densities for 2005-2009 and GEOS-Chem using NOx dependent yields of formaldehyde from isoprene oxidation. Data are filtered for formaldehyde from other sources like biomass burning and anthropogenic activity, and dusty scenes that impact retrieval of formaldehyde from UV/visible measurements. Smearing is also corrected for using GEOS-Chem. Missing values over Africa are set to -1.26e+30. Of the valid data over Africa, there are some negative values that results from scenes with formaldehyde columns close to the instrument detection limit.