Creatine ethyl ester (CEE) is less stable than creatine monohydrate in acidic environments and does not promote greater muscle creatine gains or training adaptations compared to CM.

Tallon et al. ... found that CEE was actually less stable than CM. It was concluded that the addition of the ethyl group to creatine actually reduced acid stability and accelerated its breakdown to creatinine... CEE supplementation did not promote greater total muscle creatine levels in comparison to placebo. In terms of training adaptations, CEE supplementation did not promote greater gains in body mass, fat-free mass, strength, or sprint performance.