The study of small bodies that have a cometary activity at a large heliocentric distance (larger than 5AU) is important for a better understanding of the physical properties of comets and their origin. Such studies require long-term monitoring and a significant observational effort. Our goal is to monitor the cometary activity and search for possible emission lines of C/2006 S3 (LONEOS), which is a distant comet that was discovered in 2006 and passed perihelion at 5.13AU in April 2012. We performed different observing runs with telescopes, ranging from 2m to 6m both in imaging and spectroscopic modes in the optical range, between 2006 and 2014. The comet C/2006 S3 (LONEOS) was a very active object with Afρ∼4000cm at its maximum of activity, corresponding to a dust production rate of 82 kg/s, considering a mean geometric albedo of 0.1 and grain outflow velocities in the range 2-22m/s. It appeared to be more active after its perihelion than before and we did not manage to detect any emission lines. Upper limits for the main cometary species that have emission bands in the optical range are provided. Our dust environment modeling is in agreement with a collimated source of dust that appeared in 2013.