A one pot catalytic system which involves Cu and an alkoxide co-catalyst has been used for methanol (MeOH) synthesis at low temperature. Up to about 92% syngas conversion per pass and more than 90% selectivity to MeOH (the rest is methyl formate) was obtained depending on the amount of catalyst employed at 100 degrees C and 20 bar syngas pressure. Low temperature methanol synthesis presents a good alternative to current technology for methanol production since the former is thermodynamically favored and gives a high yield per pass. Cu particles sized around 10 +/- 5 nm were found to be involved in the catalytic process. Cu nanoparticles of increasing size was synthesized by varying temperature. However, methanol production decreased with increasing Cu nanoparticle size. Moreover, the maximum conversion at the end of each successive batch declined as a function of the number of cycles performed. Decrease in catalyst activity corresponded to Cu nanoparticle densification, suggesting agglomeration to be a major catalyst deactivation pathway.