Oil-absorbent skimmers of the present invention include an upper oil-absorbent flotation head that floats on water and several absorbent strands attached to the underside of the flotation head. The flotation head has a liquid-permeable cover with absorbent strips inside. The absorbent strips and strands are made of oil-absorbing materials that resist absorption of water. The passive oil-absorbent skimmers may be free-floating and may be used in stormwater catch basins, water holding tanks, vaults, sumps, bilges and the like for capturing hydrocarbons such as oil and oil-based liquids.