Polymer miscibility was found for a blend system comprising of a new poly(aryl ether ketone) and a poly(ether imide). Phase homogeneity was preliminarily confirmed using optical and scanning electron microscopy, indicating that the scales of phase homogeneity in the blends were beyond the resolution limits of either microscopy. A composition-dependent, single glass transition temperature (T-g) in the PAEK/PEI blends within the full range of composition was observed using differential scanning calorimetry (DSC). The thermal transition breadth also suggests that the scales of mixing are fine and uniform.