Electrodeposited films of electronically conducting polymer (ECP) films (polypyrrole, polythiophene and their derivatives) are insertion materials whose thickness is expected to vary in the course of electrochemically driven doping/undoping processes [1]. There are not so many techniques allowing in-situ measurements of thickness or thickness variations with a nanometric resolution. As a consequence, dimensional variations of thin films of insertion materials as a function of their redox state are only rarely investigated nowadays even though they give birth to more and more numerous risks arising from energy conversion or storage devices (see for example explosion of the battery of famous smartphones). In this talk, a brief overview of innovative methodologies associating in-situ atomic force microscopy (AFM) and various electrochemical techniques and dedicated to in-situ measurements of thickness variations of ECPs during their electrochemical conditioning will be introduced. Such methodologies can all be considered as different versions of the electrochemical atomic force microscopy (EC-AFM) technique. They actually associate usual working modes of AFM, such as contact mode or amplitude modulation-AFM (AM-AFM), with well adapted electrochemical techniques such as cyclic voltammetry (CV), chronoamperometry (CA) but also electrochemical impedance spectroscopy (EIS), sinusoidal voltammetry (SV), or advanced cyclic voltammetry (ACV). This latter technique is particularly interesting because it allows resting periods to be applied in between two consecutive potential cycles. Throughout our investigations, our purpose was to establish, each time it was possible, correlations between the thickness variations measured using EC-AFM and ion and solvent exchanges occurring at the ECP film/solution interface as a result of the electrochemical doping/undoping of these ECP films. Other properties of ECPs can be measured in the course of EC-AFM experiments. Among them, one can cite absolute thickness or mechanical properties of ECPs such as hardness, expected to be directly related to their porosity, and/or to their permeability to the electrolytic solution, and our goal was to correlate them with data extracted from electrochemical techniques. Advantageously, such EC-AFM methodologies allow moreover many potential scans to be applied on the same sample, which allows other fascinating issues such as relaxation or ageing processes of ECPs to be further investigated. This contribution will be mainly focused on results obtained with polypyrrole or poly-(ethylene-dioxythiophene) thin films electrodeposited from aqueous electrolytic solutions in the presence of either bulky anions such as hexasulfonated calix[6]arenes [2,3] or dodecylsulfate anions or much smaller anions such as perchlorate anions. References : 1) J. Heinze, B.A. Frontana-Uribe,, S. Ludwigs, Chem. Rev. 2010, 110, 4724-4771. 2) L.T.T. Kim, C. Gabrielli, A. Pailleret, H. Perrot, Electrochem. and Solid State Lett., (2011), 14(11), F9-F11. 3) L.T.T. Kim, C. Gabrielli, A. Pailleret, H. Perrot, Electrochim. Acta, (2011), 56, 3516-3525.