**Abstract**

Heavy metals have a huge impact on the environment due to their toxicity and bioaccumulation capacity. A great variety of methods can be used to the determination. The electrochemical methods are one of the best options due to their sensitivity, selectivity, and rapidness. They are based on the use of electrochemical cells made of different materials depending on the analyte to determine. An eco-friendly cheap option that has earned big importance is paper-based electrodes, which are formed by a cellulose matrix modified with conductive inks. Carbon ink is the most used, and it can be modified with nanoparticles to increase sensitivity. Alternatively, metallic surfaces or "films" such as mercury or bismuth can improve the determination of heavy metals because of their interactions with the film. This chapter focuses on the methods to determination of heavy metals based on their affinity with different nanomaterials or films on low-cost electrode substrates.

**Keywords:** paper-based, heavy metals, nanomaterials, films, bismuth
