The　time-varying　gravity　field　models　derived　from　the　Gravity　Recovery　and　Climate　Experiment　(GRACE)　satellite　mission　suffer　from　pronounced　longitudinal　stripe　errors　in　the　spatial　domain.　A　potential　way　to　mitigate　such　errors　is　to　combine　GRACE　data　with　observations　from　other　sources.　In　this　study,　we　investigate　the　impacts　on　GRACE　monthly　gravity　field　solutions　of　incorporating　the　GPS　data　collected　by　the　Gravity　Field　and　Steady-State　Ocean　Circulation　Explorer　(GOCE)　mission.　To　that　end,　we　produce　GRACE/GOCE　combined　monthly　gravity　field　solutions　through　combination　on　the　normal　equation　level　and　compare　them　with　the　GRACE-only　solutions,　for　which　we　have　considered　the　state-of-the-art　ITSG-Grace2018　solutions.　Analysis　in　the　spectral　domain　reveals　that　the　combined　solutions　have　a　notably　lower　noise　level　beyond　degree　30,　with　cumulative　errors　up　to　degree　96　being　reduced　by　31%.　A　comparison　of　the　formal　errors　reveals　that　the　addition　of　GOCE　GPS　data　mainly　improves　(near-)　sectorial　coefficients　and　resonant　orders,　which　cannot　be　well　determined　by　GRACE　alone.　In　the　spatial　domain,　we　also　observe　a　significant　reduction　by　at　least　30%　in　the　noise　of　recovered　mass　changes　after　incorporating　the　GOCE　GPS　data.　Furthermore,　the　signal-to-noise　ratios　of　mass　changes　over　180　large　river　basins　were　improved　by　8-20%　(dependent　on　the　applied　Gaussian　filter　radius).　These　results　demonstrate　that　the　GOCE　GPS　data　can　augment　the　GRACE　monthly　gravity　field　solutions　and　support　a　future　GOCE-type　mission　for　tracking　more　accurate　time-varying　gravity　fields.