This work studied the microstructure of binary aluminum-copper powders (2-5 wt% Cu) produced by inert gas atomization. Gas atomization is one of the key processing techniques for producing alloy powders used in powder metallurgy production and, more recently, for cold gas dynamic spray deposition. The micro- and nanostructures were studied using SEM, TEM, and precession electron diffraction. These powders all exhibited a cellular solidification structure with the Al2Cu, theta, phase along the cell boundaries. The extent of cell boundary coverage increased with increased copper content. The cell size was quite small, approximately 2 microns, and varied only slightly with copper content. Guinier-Preston zones were not observed in the gas atomized powders even after eighteen months of natural aging. Small Al2Cu precipitates were present inside the cells, but with random crystallographic orientations. Using helium gas, these alloy powders were successfully deposited as high density coatings via the cold spray process.