LiMnPO4 was synthesized using a sol-gel method and tested as a cathode material for lithium ion batteries. After calcination at temperatures between 520 and 570 degrees C particle sizes in the range of 140 to 160 nm were achieved. Subsequent dry ballmilling reduced the diameter to 130 +/- 10 nm. Reversible capacities of 156 mAh/g at C/100 and 134 mAh/g at C/10 were measured. At 92 and 79% of the theoretical values, respectively, these are the highest values reported to data for this material. At faster charging rates, the electrochemical performance was found to be improved when smaller particles were used.