Wandsworth students found traffic cones and old shoes among the debris as they took part in a clear up along the shores of the Thames.
Ashcroft Academy pupils took part in a litter pick by Battersea Bridge as part of National Science and Engineering week, in an event organised by the Thames Tideway Tunnel project and charity Thames 21.
The year nine students also tested the quality of the river water.
Ashcroft science teacher Rehaan Malik said: “They don’t get an opportunity like this every day. "Most of the children live near the river but have never actually been right next to it.
"It’s a really engaging and relevant way to get them interested in science and the environment.”
The students were given certificates accredited by British Science Association in recognition of their work.