We have studied the formation of Pd-nanodots on SiO₂ from ultrathin Pd films being exposed to remote hydrogen plasma at room temperature, in which parameters such as the gas pressure and input power to generate H₂ plasma and the Pd film thickness were selected to get some insights into surface migration of Pd atoms induced with atomic hydrogen irradiation and resultant agglomeration with cohesive action. The areal dot density was controlled in the range from ∼3.4 to ∼ 6.5×10¹¹ cm^-2 while the dot size distribution was changed from ∼7 to ∼1.5 in average dot height with ∼40% variation in full-width at half maximum. We also fabricated MOS capacitors with a Pd-nanodots floating gate and confirmed the flat-band voltage shift in capacitance-voltage characteristic due to electron injection to and emission from the dots floating gate.