RNA interfering technology has become a successful strategy for targeted gene silencing through the use of efficient delivery systems. A nanocarrier must be especially designed when considering unusual routes due to RNA instability in biological medium. Lung delivery provides extensive area of absorption and alveolar deposition, non-invasiveness and local action. However, biological barriers such as lung mucus are a great challenge to the efficient delivery of nanocarriers for therapeutic purpose. Here, we studied the diffusion of mucopenetrating lipoplexes (LX) modified with hyaluronic acid (HA) and polyethylene glycol (PEG) for the local delivery of siRNA to the lungs. PEG is commonly used for the design of mucus-penetrating nanoparticles, while the combination with HA polymer provides additional selective targeting to lung tumor cells overexpressing CD44 receptors. Cationic liposomes modified with HA and PEG in the respective concentrations of 10 and 15% (w/v) and 5, 10 and 15% (molar ratio) were prepared by ethanol injection and mixed with siRNA molecules for LX formation. Multiple particle tracking (MPT) was performed ex vivo to evaluate the influence of the hydrophilic polymers in the particles movement in fresh human airway mucus. In vivo LX distribution in the lungs of mice was analyzed by fluorescence microscopy after intratracheal administration. LX modified with both polymers showed increasing diffusion with Brownian-like trajectories in mucus samples along with the presence of siRNA. PEG12%/HA15%-LX at the charge ratio ±4:1 were more widely distributed throughout mice lungs. Non-PEGylated HA15%-LX at the charge ratio ±4:1 diffused comparably to PEGylated LX, as opposed to non-modified LX, which were trapped in the mucus. LX interaction with A549 lung cells showed that the presence of HA improved cell uptake despite PEGylation, demonstrating that appropriate particle coating with mucoinert polymers and tuning surface charge compose an efficient strategy for siRNA delivery to CD44-expressing lung cells.