Abstract Patratu coal based thermal power plant of Jharkhand, India uses Gondwana coal and generates ≈ 0.259 metric tonnes of fly ash. Only 3% of fly ash produced is utilized and rest is dumped as slurry, in the slurry pond and in the low-lying areas of the nearby villages. This study was aimed to find the mobility of metals in the fly ash samples by sequential extraction as well as to evaluate the ecological risk of the fly ash. The transformation of surface morphology after each step of sequential extraction was also studied by SEM-EDX. The results revealed that 13% of Cd and 1% of Ni was water soluble 48% of Ni, 23% of Mn, and 7% of Cd were in exchangeable fraction. The proportion in carbonate bound fraction was Cd (32%), Cu (15%), Zn (12%), Mn (6%), and Ni (3%) of the total metal content. Whereas, the proportion in Fe–Mn oxide bound fraction was Fe (46%), Mn (14%), Zn (13%) and Ni (3%); in organic bound fraction was Pb (38%), Cu (33%), Zn (16%), Cr (15%), Ni (13%), Mn (7%), Fe (6%), and Cd (2%) and in residual fraction was Cr (85%), Pb (62%), Mn (50%), Zn (59%), Cu (44%), Fe (47%), and Cd (25%). Pollution load index of metals in fly ash was more than one. Ecological risk index was also above 600. These values signify high ecological and pollution risk of the fly ash due to presence of heavy metals. So, implementation of proper remediation techniques is necessary to reduce the ecological risk of the fly ash.