The effect of 1-pyrenesulfonicacid sodium salt (1-PSA), tetracyanoethylene (TCNE) and tetrafluoro-tetracyanoquinodimethane (F4-TCNQ) on charge transport properties of reduced graphene oxide (RGO) is examined by measuring the transfer characteristics of field-effect transistors and co-planar time-of-flight photocurrent technique. Evidence of p-type doping and a reduction of mobility of electrons in RGO upon deposition of these materials is observed. Time-resolved photocurrent measurements show a reduction in electron mobility even at submonolayer coverage of these materials. The variation of transit time with different coverages reveals that electron mobility decreases with increasing the surface coverage of 1-PSA, TCNE and F4-TCNQ to a certain extent, while at higher coverage the electron mobility is slightly recovered. All three molecules show the same trend in charge carrier mobility variation with coverage, but with different magnitude. Among all three molecules, 1-PSA acts as weak electron acceptor compared to TCNE and F4-TCNQ. The additional fluorine moieties in F4-TCNQ provides excellent electron withdrawing capability compared to TCNE. The experimental results are consistent with the density functional theory calculations. Display omitted •RGO FETs, exhibit a positive shift of the charge-neutrality point due to deposition of organic semiconductor layer.•The amount of shift varies with the molecule electron affinity.•The electron mobility is quenched by the presence of F4-TCNQ and TCNE, while 1-PSA don’t affect the electron mobility.•With increasing the coverage of 1-PSA, the electron mobility drops and then slightly recovers at higher coverages.•The change in the electron mobility is due to effect of teh RGO/organic-layer interface dipole field.