diff --git a/pkg/rpc/client.go b/pkg/rpc/client.go
index 2e29bfaa5..2df32a43f 100644
--- a/pkg/rpc/client.go
+++ b/pkg/rpc/client.go
@@ -8,6 +8,7 @@ import (
 	"net"
 	"net/http"
 	"net/url"
+	"sync"
 	"time"
 
 	"github.com/CityOfZion/neo-go/pkg/wallet"
@@ -25,23 +26,26 @@ var (
 type Client struct {
 	// The underlying http client. It's never a good practice to use
 	// the http.DefaultClient, therefore we will role our own.
-	http.Client
-	endpoint *url.URL
-	ctx      context.Context
-	version  string
-	Wif      *wallet.WIF
-	Balancer BalanceGetter
+	cliMu      *sync.Mutex
+	cli        *http.Client
+	endpoint   *url.URL
+	ctx        context.Context
+	version    string
+	wifMu      *sync.Mutex
+	wif        *wallet.WIF
+	balancerMu *sync.Mutex
+	balancer   BalanceGetter
 }
 
 // ClientOptions defines options for the RPC client.
 // All Values are optional. If any duration is not specified
 // a default of 3 seconds will be used.
 type ClientOptions struct {
-	Cert           string
-	Key            string
-	CACert         string
-	DialTimeout    time.Duration
-	RequestTimeout time.Duration
+	Cert        string
+	Key         string
+	CACert      string
+	DialTimeout time.Duration
+	Client      *http.Client
 	// Version is the version of the client that will be send
 	// along with the request body. If no version is specified
 	// the default version (currently 2.0) will be used.
@@ -55,20 +59,18 @@ func NewClient(ctx context.Context, endpoint string, opts ClientOptions) (*Clien
 		return nil, err
 	}
 
-	if opts.DialTimeout == 0 {
-		opts.DialTimeout = defaultDialTimeout
-	}
-	if opts.RequestTimeout == 0 {
-		opts.RequestTimeout = defaultRequestTimeout
-	}
 	if opts.Version == "" {
 		opts.Version = defaultClientVersion
 	}
 
-	transport := &http.Transport{
-		DialContext: (&net.Dialer{
-			Timeout: opts.DialTimeout,
-		}).DialContext,
+	if opts.Client == nil {
+		opts.Client = &http.Client{
+			Transport: &http.Transport{
+				DialContext: (&net.Dialer{
+					Timeout: opts.DialTimeout,
+				}).DialContext,
+			},
+		}
 	}
 
 	// TODO(@antdm): Enable SSL.
@@ -76,30 +78,73 @@ func NewClient(ctx context.Context, endpoint string, opts ClientOptions) (*Clien
 
 	}
 
+	if opts.Client.Timeout == 0 {
+		opts.Client.Timeout = defaultRequestTimeout
+	}
+
 	return &Client{
-		Client: http.Client{
-			Timeout:   opts.RequestTimeout,
-			Transport: transport,
-		},
-		endpoint: url,
-		ctx:      ctx,
-		version:  opts.Version,
+		ctx:        ctx,
+		cli:        opts.Client,
+		cliMu:      new(sync.Mutex),
+		balancerMu: new(sync.Mutex),
+		wifMu:      new(sync.Mutex),
+		endpoint:   url,
+		version:    opts.Version,
 	}, nil
 }
 
+func (c *Client) WIF() wallet.WIF {
+	c.wifMu.Lock()
+	defer c.wifMu.Unlock()
+	return wallet.WIF{
+		Version:    c.wif.Version,
+		Compressed: c.wif.Compressed,
+		PrivateKey: c.wif.PrivateKey,
+		S:          c.wif.S,
+	}
+}
+
 // SetWIF decodes given WIF and adds some wallet
 // data to client. Useful for RPC calls that require an open wallet.
 func (c *Client) SetWIF(wif string) error {
+	c.wifMu.Lock()
+	defer c.wifMu.Unlock()
 	decodedWif, err := wallet.WIFDecode(wif, 0x00)
 	if err != nil {
 		return errors.Wrap(err, "Failed to decode WIF; failed to add WIF to client ")
 	}
-	c.Wif = decodedWif
+	c.wif = decodedWif
 	return nil
 }
 
+func (c *Client) Balancer() BalanceGetter {
+	c.balancerMu.Lock()
+	defer c.balancerMu.Unlock()
+	return c.balancer
+}
+
 func (c *Client) SetBalancer(b BalanceGetter) {
-	c.Balancer = b
+	c.balancerMu.Lock()
+	defer c.balancerMu.Unlock()
+
+	if b != nil {
+		c.balancer = b
+	}
+}
+
+func (c *Client) Client() *http.Client {
+	c.cliMu.Lock()
+	defer c.cliMu.Unlock()
+	return c.cli
+}
+
+func (c *Client) SetClient(cli *http.Client) {
+	c.cliMu.Lock()
+	defer c.cliMu.Unlock()
+
+	if cli != nil {
+		c.cli = cli
+	}
 }
 
 func (c *Client) performRequest(method string, p params, v interface{}) error {
@@ -121,7 +166,7 @@ func (c *Client) performRequest(method string, p params, v interface{}) error {
 	if err != nil {
 		return err
 	}
-	resp, err := c.Do(req)
+	resp, err := c.Client().Do(req)
 	if err != nil {
 		return err
 	}
diff --git a/pkg/rpc/rpc.go b/pkg/rpc/rpc.go
index 8b444f2c3..a90f8be54 100644
--- a/pkg/rpc/rpc.go
+++ b/pkg/rpc/rpc.go
@@ -106,7 +106,7 @@ func (c *Client) SendRawTransaction(rawTX string) (*response, error) {
 }
 
 // SendToAddress sends an amount of specific asset to a given address.
-// This call requires open wallet. (`Wif` key in client struct.)
+// This call requires open wallet. (`wif` key in client struct.)
 // If response.Result is `true` then transaction was formed correctly and was written in blockchain.
 func (c *Client) SendToAddress(asset util.Uint256, address string, amount util.Fixed8) (*SendToAddressResponse, error) {
 	var (
@@ -118,8 +118,8 @@ func (c *Client) SendToAddress(asset util.Uint256, address string, amount util.F
 			assetId:  asset,
 			address:  address,
 			value:    amount,
-			wif:      *c.Wif,
-			balancer: c.Balancer,
+			wif:      c.WIF(),
+			balancer: c.Balancer(),
 		}
 		resp     *response
 		response = &SendToAddressResponse{}