Due to the wide applications of inkjet printers in industry and our daily life, characterization of liquid droplets from inkjet printers, particularly the behaviors of the impact and diffusion of the droplets on the surface of and inside porous medium is of great interest. One conventional characterization method uses high-speed optical cameras to record the images of the motion of the liquid droplets. However, this method does not have sufficient time resolution to capture the transient motion of the liquid droplet and does not provide any information of the diffusion process inside the medium because the porous media such as paper are not transparent. In this study, we use an optical scattering method to investigate the behavior of liquid droplets in porous media both theoretically and experimentally. The working principle is based on measuring the liquid-induced optical scattering from a laser beam to probe the impact and diffusion processes of the droplets. The diffusion characterization was conducted on conventional coated and uncoated printing paper samples from Hewlett Packard. The influence of thermal effects from the laser and the distance between the printer and the sample was also analyzed. The correlation between the optical transmission and the penetration depth was studied. In addition, we measured the transient optical signals with nano-second resolution to reveal the liquid droplet oscillation on a glass surface. Our experimental results match the numerical simulation, which proves that the optical scattering method is feasible tool for further characterizations of the liquid droplets from inkjet printers.