Hydrogenated amorphous silicon (a-Si:H) has been attracting a lot of attention for last decades, because of its perspectives in thin film optoelectronics (e.g. solar cells, active matrix of liquid crystal displays). It combines low cost with a processing mechanism capable with large scale technologies. Low temperatures during the deposition process allow using inexpensive and lowmelting substrates. The main issues with a-Si:H films is the high order of dangling bonds which act as recombination centers that strongly reduce the carrier lifetime and make the efficiency of the solar cell as low as around 10 %. Additionally, this initial efficiency will halfway decrease when exposed to sunlight which is known as the Staebler-Wronski effect (SWE) [1]. In order to reduce the SWE in solar cells, hybrid a-Si/nc-Si tandem modules have been developed [2]. Such modules are able to achieve both higher efficiency and stability compared with single a-Si:H solar cells. For optimization of technological process of tandem solar cells production one can use a femtosecond laser-induced crystallization of a-Si:H thin films. The laser-based treatment of a-Si:H may solve its efficiency and stability issues in a one-step process. a-Si:H films with a thickness of 300 nm were deposited onto quartz substrates using PECVD method. The a-Si:H film was deposited at a rate about 2 Å/s in an argon (Ar) diluted silane (SiH4) environment at a substrate temperature of 250 oC. The samples were treated using a femtosecond Yb:KGW laser system. The laser system delivered pulses at a repetition rate of 200 kHz with a pulse wavelength of 1030 nm and a duration of 500 fs. The beam spot was circular with beam diameter of 15 μm on the film surface. To prepare the samples for measurements films were scanned by laser beam with the scanning speed of 5 mm/s. The scanning step was 2 μm. To carry out the electrical and photoelectric measurements aluminum contacts were deposited on the surface of prepared films. The gap between the contacts was perpendicular to the laser beam scanning direction. Distance between contacts and their length were 0.5 and 4 mm correspondingly. Averaged laser beam power was varied continuously from 25 to 100 mW. We have investigated the effect of femtosecond laser treatment of hydrogenated amorphous silicon films on their structural, optical and photoelectric properties. When crystalline volume fraction of the treated samples was around 7 % sufficient increase (by 4 orders of magnitude) of dark conductivity was observed. We have attributed such behavior to change in charge carrier transport mechanism from amorphous to nanocrystalline. However, the shape of the spectral dependences of absorption coefficient of all investigated samples corresponded to that of a-Si:H. This question still remains uncertain and needs further investigation. It was shown that samples treated by femtosecond laser pulses are more stable to photodegradation in comparison with untreated films. It was also found that starting from some values of laser fluence the effect of spallation and film oxidation occurred.