We analyze the;primordial protogalactic gas to investigate the role of
thermal instabilities in the formation of condensations that could co
ntribute to the MACHO mass function. We find that the previrialized pr
otogalaxy could have undergone a thermally unstable regime, which defi
nes a peak in mass condensations starting around 0.1 M. after being re
processed by the environment that may be identified as giving origin t
o the MACHOs. Effects of magnetic fields on this instability-driven MA
CHOs scenario are also addressed.