LiCr2Y Ni0.5−Y Mn1.5−Y O4 (0< Y ≤0.2) spinels have been synthesized by a sucrose-aided combustion method. Two sets of Cr-doped samples have been obtained by heating the “as-prepared” samples at 700 and 900°C for 1h. X-ray diffraction and thermogravimetric data show that pure and single phase spinels with similar lattice parameter have been synthesized. The homogeneity and the sub-micrometric particle size of the spinels have been shown by SEM and TEM. The main effect of the temperature is to increase the particle size from ≈50 to ≈500nm, on heating from 700 to 900°C. The study of the influence of Cr-dopant content and thermal treatment on the electrochemical properties at 25°C and at 55°C has been carried out by galvanostatic cycling in Li-cells. The discharge capacity (≈130mAhg−1) does not noticeably change with the synthesis conditions; but the cycling performances are strongly modified. Key factors that control the cycling performances have been determined. The most highlighted result is that spinels heated at 900°C with Y ≤0.1 have very high capacity retention at 55°C (>96% after 40 cycles, cyclability >99.9% by cycle) indicating that metal doping is a new approach to prepare 5V LiNi0.5Mn1.5O5-based cathodes with excellent cycling performances at high temperature.