The role of the particle size on the electrochemical properties at 25 and at 55°C of the LiCr0.2Ni0.4Mn1.4O4 spinel synthesized by combustion method has been determined. Samples with different particle size were obtained by heating the raw spinel from 700 to 1100°C, for 1h in air. X-ray diffraction patterns revealed that all the prepared materials are single-phase spinels. The main effect of the thermal treatment is the remarkable increase of the particles size from ∼60 to ∼3000nm as determined by transmission electron microscopy. The electrochemical properties were determined at high discharge currents (1C rate) in two-electrode Li-cells. At 25 and at 55°C, in spite of the great differences in particle size, the discharge capacity drained by all samples is similar (Q dch ≈135mAhg−1). Instead, the cycling performances strongly change with the particle size. The spinels with Φ >500nm show better cycling stability at 25 and at 55°C than those with Φ <500nm. The samples heated at 1000 and 1100°C, with high potential (E ≈4.7V), elevate capacity (Q ≈135mAhg−1), and remarkable cycling performances (capacity retention after 250 cycles >96%) are very attractive materials as 5V-cathodes for high-energy Li-ion batteries.