Abstract Linear poly(ether ether ketone) (LPEEK) with high melt viscosity was blended with hyperbranched poly(ether ether ketone) (HPEEK) to enhance its melt processability without sacrificing its comprehensive performance. The advantage of using HPEEK is due to its unique spherical shape, low melt viscosity and ready availability. Rheological measurements show that blending LPEEK with as little as 1 wt% HPEEK results in about 17% reduction of melt viscosity. LPEEK/HPEEK blends only show one glass transition temperature, indicating complete miscibility, which results from the similar molecular structure of the two components. The HPEEK component, as rheology modifier, accelerates the crystallization rate of LPEEK. Notably, with the addition of 3 wt% HPEEK, the mechanical properties of LPEEK are improved. Good miscibility is proposed to be responsible for the improved mechanical properties. Moreover, the addition of HPEEK does not decrease the thermal stability of LPEEK. Copyright © 2011 Society of Chemical Industry.