The low-temperature specific heat of alpha-phase of (BEDT-TTF)(2)MHg(S
CN)(4) (M=K, Rb, NH4), where BEDT-TTF is bis(etylenedithio) tetrathiaf
ulvalene, is studied. The electronic specific heat coefficient (gamma)
estimated from the data between 1K and 2.3K amounts to 5.3, 10.3, 28.
8mJ/mol K-2 for M=K, Rb and NH4, respectively. The K-salt does not hav
e distinct anomally around 8K within the precision of our experiments,
implying that the transition occurs with a gradual change of electron
ic structure.