The present invention relates to a process for degassing an aqueous solution containing a hydroformylation product and separating a volatile metal species from gaseous stream to inhibit or prevent deposition of a solid material from the gaseous stream. To separate the volatile metal species from the gaseous stream, the gaseous stream is either 1) contacted with a liquid that separates the volatile metal species, or a reaction product thereof, from the gaseous stream; 2) passed through a microfilter having a pore size of 2 .mu.m or less; or 3) contacted with an adsorbent material.