Two frothers covering a very broad range from weak and selective (DF-200) to powerful (DF-1012) flotation performance were chosen to test, the effect of frothers on bubble generation and bubble coalescence in a laboratory scale flotation cell. In two-phase, gas-liquid systems, the experiments showed that the frothers affect both the bubble breaking process and the coalescence of bubbles. While the DF-200 frother, characterized by much larger critical coalescence concentration (CCC) values than DF-1012, has the ability to produce finer bubbles at concentrations exceeding the CCC value, the bubbles generated in the DF-1012 solutions at concentrations exceeding CCC are much larger.