The present invention relates to a process for preparing cyclic acetals having general formula (I) wherein Y and Y′, equal to or different from each other, are selected from H and a group OR, R being a linear or branched alkyl containing from 1 to 8 carbon atoms, comprising at least the following phases: (i) providing a reaction mixture comprising at least one vicinal diol having formula (II) Z—CH2-CHOH—CH2OH wherein Z is selected from H and a group OR′, R′ being a linear or branched alkyl containing from 1 to 8 carbon atoms, said mixture being substantially free of aldehydes having general formula R1—CHO, wherein R1 is a linear or branched alkyl containing from 1 to 6 carbon atoms, possibly substituted by an alkoxide group OR111, wherein RIII is an alkyl containing from 1 to 4 carbon atoms; (ii) thermally treating said reaction mixture at a temperature within the range of 100° C.-300° C. in the presence of at least one acid catalyst, obtaining said compound having formula (I). The acetals having formula (I) can be used as fuel components.