This paper highlights the potentialities of a very simple electrochemical set-up for studying the electrodeposition of thin film in real time by in situ XANES measurements. This study focuses on birnessite, a promising non-toxic manganese oxide for various applications. The main originality of this device comes from its window used as a counter electrode allowing the electrodeposition on large surfaces (some cm2), exactly like in a classical electrochemical cell. The quality of the in situ XANES measurements is comparable to that of ex situ measurements demonstrating the real interest of this continuous flow electrochemical cell for characterising compounds during electrochemical measurements. Moreover, the electrodeposited thin films are similar to those obtained in a classical electrochemical cell, as illustrated by the ex situ characterizations (XANES, XRD and SEM). Thus, this promising set-up will allow the studies of numerous materials in the future.