Transient absorption spectroscopy is convenient to probe the photophysical and photochemical effects of semiconductor nanoclusters and heterogeneous charge transfer events at the semiconductor interface. The fast kinetic spectroscopy not only enables the detection of photogenerated transients in the femtosecond to microsecond time domain, but also enables understanding of the photophysical and photochemical properties that are unique to semiconductor nanoclusters. For example, this technique has provided some useful kinetic and mechanistic information of size quantization effects, non-linear optical effects, electro and photochromic effects, photocurrent generation, photocatalysis and charge rectification properties of semiconductor nanoclusters. These properties are controlled by charge separation, charge trapping and heterogeneous charge transfer at the semiconductor interface under UV and visible light irradiation. Some recent developments in this area are presented here.