The present invention relates to a process for preparing aldehydes by reacting an α,β-unsaturated carboxylic acid or a salt thereof with carbon monoxide and hydrogen in the presence of a catalyst comprising at least one complex of a metal of transition group VIII of the Periodic Table of the Elements with at least one compound of the formula (I), where Pn is pnicogen; W is a divalent bridging group having from 1 to 8 bridge atoms between the flanking bonds; R1 is a functional group capable of forming at least one intermolecular, noncovalent bond with the —X(═O)OH group of the compound of the formula (I); R2, R3 are each in each case optionally substituted alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl or together with the pnicogen atom and together with the groups Y2 and Y3 if present form an optionally fused and optionally substituted 5- to 8-membered heterocycle; a, b and c are each 0 or 1; and Y1,2,3 are each, independently of one another, O, S, NRa or SiRbRc, where Ra,b,c are each H or in each case optionally substituted alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl; and the use of the above-described catalyst for the decarboxylative hydroformylation of α,β-unsaturated carboxylic acids.